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Bookmark Technology
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Shock survey suggests most investors think Bitcoin won't top $50K by 2030
Max 1 month ago in Celebrity 0
British Virgin Islands-based institutional mining platform, Genesis Mining, has published the findings from a survey of 1,000 current and former U.S.-based Bitcoin investors — two-thirds of whom believe BTC is a better long-term store of value than the dollar.
More than half of respondents believe Bitcoin will beat out gold, real estate, and the stock market over the five to 10 years, with 65% expressing faith that BTC's value will continue to appreciate with time.
The bear case
But despite the apparently favorable sentiment, just 17% of those surveyed predicted that Bitcoin's price would exceed $50,000 by 2030. This would only require the price to increase by 160% over the next 10 years, while BTC has already gained 166.5% during 2020 so far.
A further 17% predicted that Bitcoin's price would actually fall over the next decade, while one sixth of respondents did not feel confident in speculating on BTC's long-term price performance.
In total 50.1% of respondents estimated that BTC will be worth $20,000 or less by 2030, one third predicted the price will be $10,000 or less, and 11.8% forecasted prices below $1,001.
Almost one-third of respondents who predict a stagnate or bearish 10-year performance expect Bitcoin to be hindered by regulations, while one fifth anticipate outright bans on cryptocurrency from governments.
Roughly 17% of non-bullish respondents expect another cryptocurrency or a central-bank issued digital currency will capture a dominant market share and supersede BTC, while 16% predict Bitcoin's historical meteoric hype-cycles will die down over time. Nearly 10% of participants do not believe "there is going to be a practical use case" for Bitcoin in future.
The bull case
On the bullish end of the spectrum, one-tenth tipped Bitcoin would be worth six-figures or more in a decade, with half of them expecting prices exceeding $500,000.
Almost 30% of bullish respondents believe Bitcoin adoption will be driven by declining trust in fiat currencies, with 25.8% anticipating "a major economic depression" will spark widespread adoption. More than half of respondents believe, "Bitcoin adoption has much room for growth" regardless of political forces external to crypto.
Who was surveyed
The survey had a good mix of investors, with one quarter allocating more than half their wealth to virtual currency investments, one quarter had crypto exposure of between 10% to 50%, another quarter had between 1% and 10% in crypto, while the rest had 1% or less of their wealth currently in virtual currency.
A recent survey from fund manager Grayscale Investments found that the COVID-19 pandemic had a positive impact on Bitcoin sentiment, with 39% of respondents describing BTC as "more appealing" amid the pandemic.
Last month, a survey of 700 high-net-worth individuals published by deVere Group found that 73% of millionaires either already own or are planning to invest in crypto assets by 2023.
GBTC has a new a competitor in the OTC Bitcoin...
Tags : 50K, Bitcoin, Investors, shock, suggests, Survey, Top, wont
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This section includes sound recordings made by agencies that were either responsible for scientific research or actively concerned with the dissemination of scientific knowledge.
The Australian Broadcasting Commission (ABC), Head Office (CA 251) was established under the Australian Broadcasting Commission Act 1932. The Commission was a government-controlled body, closely modelled on the British Broadcasting Commission, responsible for broadcasting music, current affairs, religious, educational and other programs. (See Chapter 3 for a more comprehensive description).
This series consists of 10" and 12" gramophone disc recordings of Australian Broadcasting Commission radio programs broadcast in South Australia. They include speeches, documentaries, plays and music. In 1991 preservation tape copies of the discs were made by the Sydney Office of the National Archives. Reference cassette copies are available.
This series consists of transcription recordings of ABC programs, including book readings, orchestral music and documentaries.
The tapes in this series are part of the series B593 (see below), which is a compilation of natural history sound tapes.
This series was recorded by the Natural History Unit of ABC Victoria. The tapes in the series record the sounds of animals, insects, reptiles, volcanos, hot springs, swamps, waterways and native village life including celebrations, atmosphere and general effects. The tapes were prepared for use in films and are arranged by program number. The material was copied from the master tapes.
Tapes in this series are part of B593 (see above).


Atheists and Christian How can I help my Low IQ friend?
Atheists and Christian my Low IQ friend doesn't want to trust God . What Should I do?
Does she sound more like Aries or Leo or Sag or Virgo Rissing?
Atheists and Christians how to convice my Low IQ to trust God?
Atheists so you believe fate in your hands?
Atheists and Christians My Low IQ friend Xuan is crazy?
she always like to said good thing about her favourite actor and actress ... She said she will still treat the actress nice even God answer their prayers but never answer hers for 20 year She said even her faith is lost but nevermind even goo to hell she will still be nice to others She said maybe God find she is not pretty enough for him to answer She believe she said I'm ugly onself can't expect soo much either. She said if God really love her he will find a way to mmake her believe She said unless she is destinied for hell She said I don't do good things because I want go to heaven that lame .
Atheists and Christians I have a question?
so Christian you claim trust God will go to heaven how about if kind hearted Atheists who help others weaker that them . if this Atheists is a saint also will go to hell because he dont trust God.
Atheists and Christians My Low Iq frend don't want trust God?
Atheists and Christians my Low IQ friend said she trust Guanyin but not God?
Atheists and Christians My Low IQ friend Xuan told me to shut up . ( mad mad mad )?
Atheists and Christian my Low IQ friend said God is trying to change her to evil?
I said God don't change people to evil She reply he does I experience it She reply he answer pretty mediacorp actress forsaken for me 20 years She said God want to turn her into jealous and evil queen like Snow White 's mother in story book She replied no she not going fall for his trap She said so someone did wrong or don't trust or loose faith deserve to be burn to hell She said this seem cold nobody deserve to hell I ask u a question so if nubitol the guy who u hate drown will u still save him ? She reply yes is not because I'm perfect is because I feel guilty She reply and I don't ask other to repent so I can never be Christian She replied I'm not smart and not pretty ask other to repent will give u think you are better than others She reply sorry I''m not that I need my inner beauty .. I don't really care if God want me in hell go a head She reply I don''t be nice to go heaven i said God protect u She reply laughs I'm protecting myself all a long whe I get bullied She said stop talking nonsense . we are all diffrent peoplle why keep forcing others She said God love is conditional not uncodtionall . She reply because she love a married man at let him go don't break the marrige She told me like that is true love She reply so don't give me crap ok I said God claim everyone is beautiful he love everyone equally She reply said female six sense are accurate and she can tell God doesn't love her I was like what ?????
Atheists and Christians my Low IQ friend doesn't want to follow God?
Atheists and Christians My Low IQ friend lost faith in God?
Atheists and Christians My Low IQ friend trust Guanyin but not God?
Atheists and Christians Proof God exist?
Which one sound more like Scorpio from my descripiton?
Which one sound more like Scorpio ?
Does she sound like Scorpio if not what ?
Does She sound more like Aries or Leo or Capriocrn or Cancer or Scorpio or Aquarius or Taurus?
Why Jesus symbol is a fish ??


Columbia Sportswear has released a brilliant new ad campaign focused around their built-in electronic heating devices and featuring world record holder Wim Hof. What is he a record holder for you ask? Wim (a.k.a. Iceman) is able to withstand extreme cold weather situations and has 18 world records to prove it.
And to think I won't even step into a semi-cold shower… this guy is crazy!
Wim Hof is crazy guy, can't imagine myself doing anything close what he does.


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Black Isle Woodturning
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Born and raised in a small Yorkshire town on the edge of the Pennines, Andy has always felt a love for adventure, the beauty of nature and an energy to design and create. After pursuing a career in mechanical and electrical engineering and sharing his passion for creativity through his work with children and young people, Andy met Rebecca and they married in 2006. A year later, and with the odds stacked against them, they set off together on a new adventure with a new purpose in the Highlands of Scotland. In the years that followed, and with the values of sustainability, quality workmanship and preservation of traditional craft at heart, Andy built a house, became a father and in 2010, created Black Isle Woodturning.
Aware of all the hard work and challenges ahead of him, Andy's purpose became clear – to preserve the ancient skill of woodturning whilst providing highly precise, creative, quality products and services that marry traditional techniques with modern technology.
Great things are done by a series of small things brought together
Today, Andy's work takes inspiration from the stunning Highland backdrop that surrounds his work space and stands for perseverance and passion. Each project he undertakes delivers precision, artistry and the highest quality woodwork. The adventure of Black Isle Woodturning continues with ever increasing, exhilarating projects for clients throughout the UK and further afield.
Andy has been accepted into the guild of master craftsmen in recognition of his expert knowledge and skill within the field of wood turning, for his demonstration of professional integrity and the high standard of his work. We are very proud of this achievement which validates the core values that underpin Black Isle Woodturning meaning that you can rest assured of receiving the highest quality products and services.
Email: info@blackislewoodturning.com
Address: The Old School, Cullicudden, Balblair, Dingwall, IV78LL
Copyright © 2023 Black Isle Woodturning | Signify Dark by WEN Themes

redpajama_set_name: RedPajamaCommonCrawl


Yes. Some geothermal heat pumps can provide all of your hot water needs at the same high efficiencies as the heating/cooling cycles. An option called a desuperheater can be added to most heat pumps. It will provide significant savings by heating water before it enters your hot water tank.


This home is an entertainer's dream! Located in one of Fresno's most prestigious neighborhoods, this one of a kind 6 bed, 4 bath home sits on nearly one acre. Upon entering you will be welcomed by high ceilings, large windows that provide the main living space with lots of natural light. Upstairs boasts a marvelous game room/loft with a large outdoor balcony, providing a beautiful view of the backyard oasis. Downstairs, the backyard greets you with a large covered patio, bbq , shuffle board court, fire pit area, free standing spa near the waterfall and a very large pebble tech pool with Bominite pool decking. Also, amongst this extravagant yard, you will find a detached structure that could be a guest house. Extra detached building in the backyard which could be used as a studio, office or extra storage. Let your imagination run wild. This house is a must see!


If you are researching and getting ready to start fertility treatment in 2019, you will see there are many different types of treatments available.
How IVF works: IVF – In Vitro Fertilisation – involves stimulating your ovaries to produce mature eggs, which are then fertilised in our laboratory with your partner's sperm or donor sperm. We monitor your embryos to look for the right stages of growth, transferring the embryo with the best pregnancy potential to your uterus so it can implant and grow for pregnancy.
What to consider:IVF can help overcome a wide range of fertility issues, from mild male factor infertility to blocked fallopian tubes or scarring, which prevent natural conception.
Success rates for IVF are largely consistent across clinics, with your individual chance of pregnancy dependent on factors such as your age, ovarian reserve and embryo quality. Your IVF cycle at Manchester Fertility will be tailored and personalised to you, using a range of advanced techniques if necessary, to maximise your chances and help you achieve pregnancy in the least number of cycles.
How ICSI works:ICSI – Intracytoplasmic Sperm Injection – is designed for male infertility. Instead of mixing sperm and eggs together, our expert lab team identifies and extracts the best healthy sperm from the sample, which are individually injected into each egg. This overcomes issues which can prevent fertilisation naturally such as low sperm count, poor moving sperm and abnormally-shaped sperm.
What to consider:ICSI is only generally advised for sperm issues. It is also advised if you are using sperm that has been surgically retrieved, or if sperm have a high level of DNA damage. Using ICSI, we are able to hand select only the healthiest sperm for use in fertility treatment.
How IUI works:IUI – Intrauterine Insemination – is the least invasive fertility treatment that is available and does not require any fertility medications, unless you have ovulation issues. Your partner's sperm or donor sperm is carefully inserted into your uterus around the time of ovulation, in the hope that the sperm fertilises the egg for pregnancy.
What to consider:For IUI to be successful, you must have no other fertility issues that would prevent the sperm reaching the egg, such as scarring or blockages, and sperm must be healthy. Because of this, IUI isn't suitable for everyone. We will advise if IUI is right for you at your consultation. You may also need a number of cycles of insemination to achieve pregnancy. If you have not conceived after three cycles, we will carry out a cycle review as you may require further fertility investigations.
How IVF with donor eggs works:Using donor eggs to have a baby involves carefully preparing your body for pregnancy, whilst at the same time fertilising eggs from your chosen donor with your partner's sperm or donor sperm in our laboratory. The best embryo is then transferred to your uterus for pregnancy.
What to consider:Donor eggs are strongly advised if you are over the age of 44 - we offer IVF up to the age of 50. But women of any age can find they need an egg donor to conceive, if they have medical conditions such as Premature Menopause, Premature Ovarian Failure or a very low ovarian reserve. You can choose to have treatment with fresh or frozen donor eggs at Manchester Fertility, from our own in-house donor bank, with frozen donor eggs a quick, cost-effective option.
Read our Guides to find out more about the fertility treatments suited to you, and book your free 1-2-1 with a Patient Advisor to talk to us about your options, including our treatment packages.
You can also call us on 0161 300 2730. We have immediate consultations available with our fertility specialists. Self-refer online and we will be in touch.
What is IVF, ICSI and IUI - and Which is Best for You?


Hey guys, long time no blog post. If you follow me on Instagram you would have already seen a preview of this outfit. This post was actually supposed to go up on Monday but unfortunately the internet connection has been so poor. I finally gave up and went to my dad's office which is where I am writing this post from. As you can probably tell from my hair, I wore this outfit a while back to run some errands for my mom. For a dressier look I would definitely go for my blue pumps.What do you think heels or flats?
Links will be updated as soon as I possibly can. Thanks for the awesome feedback in my last post.
Colour blue fits you perfectly dear!
I love it with the heels, but the those flats are too cute too! Lovely post!
I think I definitely prefer the blue pumps. I just love your blog, you inspire me so much! Keep up the great work girl.
Defo heels- Lovely pop and play of colour!
You look very beautiful in this outfit. Great ensemble! :) Love both for different occasions innit.
I absolutely love the pops of blue here and I'd definitely go with the heels, they look gorgeous on you!!!


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Xconomy Detroit Ann Arbor
Roche Pays $40M to Use Amunix Pharma's Half-Life Extension Tech
Foodspotting CEO: It's About Discovery, Not Food Porn
Building a Better 3D Bioprinter: GE Healthcare and ASLS Combine Tech
C. Titus Brown
Professor, Michigan State University
Alfred Spector
VP of Research and Special Initiatives, Google
Elizabeth Hagerman
Vice President for Corporate Engagement, Rose-Hulman Institute of Technology
Bill McKeon
Vice president, chief strategy and operating officer of the Texas Medical Center
Art Pappas
Managing Partner at Pappas Ventures
Detroit/Ann Arbor Home
Detroit/Ann Arbor Events
X Lists
VC / M&A Deals
MCWT Aims to Make Michigan the Top State for Women in Technology
Sarah Schmid Stevenson
The tech industry has a well-known gender diversity problem, but in Michigan, there's a group working to make the Great Lakes state a leader in terms of recruiting and inspiring women working in technology.
The Michigan Council of Women in Technology (MCWT) began in 2000 as a networking organization for working women. Since then, it has evolved. In addition to supporting Michigan's female IT workforce, the MCWT's 700-plus members are also focused on numerous outreach and mentoring programs meant to get girls and young women interested in STEM careers.
Last month, the MCWT raised $306,000 during its annual gala to expand these programs; a separate three-year, $75,000 donation from Ford will allow the group to lease office space in Dearborn, MI, for the first time in its history.
"When the MCWT started, it was a group of women working in tech, typically for the automotive industry, who said, 'There aren't many of us, but we really want to change that,'" says MCWT president Cindy Warner, managing partner of cloud strategy and solutions for IBM's global business services unit. "These women needed support and someone to share ideas with. The council started as a mentoring organization, but today, we're working to significantly improve the number of women working in tech and making Michigan the number one place for women in tech."
The MCWT is especially interested in connecting with girls in grades 3 through 8 to build awareness of the options available when it comes to a career in tech. "A lot of them don't even have technology on their radar," Warner explains. "Nobody has talked to them about it, or they think they don't like math enough, so they discount it."
The MCWT has established a program called Girls are IT—run jointly with University of Michigan-Dearborn, University of Detroit Mercy, and Lawrence Tech—that convenes hundreds of local middle school girls each year for a three-quarter day program. The girls attend workshops hosted by technology corporations that teach participants what it's like to work in different segments of the technology industry. This year's program drew more than 400 girls, and Warner is aiming to double that number in 2015.
Just last week, the MCWT hosted a website design competition where 18 high school girls took home a combined $2,775 in prizes. It was the culmination of a two-month contest between 103 teams with 144 young women from 30 Michigan high schools. (The finalists' websites can be viewed here.)
Warner says the website design competition is part of a strategy for reaching out to teenage girls that is heavy in mentorship and relationship-building. "If they do go on to study in a STEM field in college, we offer not only scholarships but a ton of help with career navigation, especially after they graduate and they've landed their first job," she says. "We want them to stay here in Michigan, because there's still a huge number that don't stay."
That mentorship becomes key after college, when a young woman might wonder what she's gotten herself into on her first tech job—where she may be the only woman working in a company's IT department. "The retention rate is really poor," Warner says. "If she doesn't know where her voice is among men, she might feel like giving up. We want to be there when it happens so we can help her find her voice again."
Warner says the council's strategy for the next three years is to continue building partnerships—she envisions one with the Girl Scouts where participants could earn a technology badge—and expanding scholarships to cover trade programs.
Warner, who has worked in technology for the past 33 years, says very little has changed in regard to the number of women in the industry, and that's the sad part: "We spend too much time giving homage to the problem and too little time designing programs to fix the problem. At the MCWT, we spend very little time on admiration. All of our programming is geared toward trying to fix the problem."
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Are you walking through life and in tune with how you are feeling every day about your daily actions? Sometimes we get used to moving each day and we forget to see how we are feeling about what we are doing or who we are with. In my time working with organizations, I have found that during difficult moments in an office environment, many people "contract" and tighten up. We have a hard time stepping back and recognizing when we are in the flow or when we are tightening up or contracting. This could be anything from handling difficult conversations, dreading meetings or talking to individuals. What can you do to expand in life more and open up better possibilities in your life? When we expand, we allow a greater sense of who we are and we work more efficiently. Jump into this week's episode to create to be in tune with how you are responding and can become a better you!


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Grain Fort
Grain, Kent, England
St James, Isle of Grain Parish Council
Demolished above ground
Concrete, granite, brick
Grain Fort is a former artillery fort located just east of the village of Grain, Kent. It was constructed in the 1860s to defend the confluence of the Rivers Medway and Thames during a period of tension with France. The fort's location enabled its guns to support the nearby Grain Tower and Garrison Point Fort at Sheerness on the other side of the Medway. It was repeatedly altered and its guns upgraded at various points in its history, before being decommissioned in 1956 when the UK abolished its coastal defence programme. It was subsequently demolished. The remnants of the fort are still visible and have been incorporated into a coastal park.
1 Strategic context
2 Construction and layout
3 Operational history
Strategic context[edit]
Map of the fortifications at the entrance to the Medway
The fort was constructed in response to a naval arms race between Britain and France. Britain's coastal defences had not been substantially upgraded since the Napoleonic Wars, but a new generation of accurate and powerful guns, mounted on fast-moving, manoeuvrable iron-clad warships, had obsoleted the existing 18th and early 19th century forts along the British coastline. The Thames was seen as particularly vulnerable; as well as being one of the country's most important trade routes, it possessed several naval installations of great importance, including the victualling yards at Deptford, the armaments works of Woolwich Arsenal, the shipbuilding yards at North Woolwich, and the magazines at Purfleet.[1]
The government's response to the increased threat was to appoint a Royal Commission on the Defence of the United Kingdom, which published a far-reaching report in 1860. It recommended that many existing forts should be upgraded or rebuilt entirely, and that new forts should be constructed to guard particularly strategic or vulnerable points along the coast. In all, around 70 forts and batteries were constructed around the English coast as a result of the Royal Commission's report.[2]
An existing gun battery, Grain Tower, already existed just off the shoreline at Grain, about 1 kilometre (0.62 mi) away from the site of the later Grain Fort. It had been built in the style of a Martello tower between 1848–55 but the introduction of powerful and accurate rifled muzzle loader (RML) guns during the 1850s made it obsolete as soon as it was completed.[3] The 1860 Commission report recommended that Grain Tower should be turned into a fully casemated fort, which would be built around the existing structure. However, the cost of doing this was seen as excessive and the proposal was dropped as part of a cost-cutting exercise to reduce the overall cost of the fort-building programme.[4] Instead, a new land fort was built at Grain, while the existing battery at Garrison Point on the Isle of Sheppey was upgraded and fortified to create Garrison Point Fort.
Construction and layout[edit]
1870 view of the forts at the mouth of the Medway: (left to right) Garrison Point, Grain Tower, Grain Fort
Grain Fort was constructed between 1861–68 to a heptagonal design. It initially had thirteen open emplacements carried on an earthwork, under which lay the magazines and linking passages. A semi-circular brick keep on a north-south alignment stood at the centre of the fort. It provided barrack accommodation for the garrison and was designed to be defensible, with loopholes in its front face to facilitate musket fire. Similarly, its gorge at the rear, where the main entrance stood, had crenelations to provide protection for defenders faced with a rearward attack. In front of the keep was a ditch, accessed via a gate at the rear of the fort. It had four caponiers that guarded the angles and were accessed via passages through the underlying structure. An inner ditch around the keep was covered by a further three caponiers and two demi-caponiers which led into the earthwork ramparts in one direction and into the keep in the other. The keep could also be accessed via a bridge which connected it with the terreplein.[5]
Operational history[edit]
Grain Fort's initial armament consisted of 13 heavy RMLs (six 11-inch, four 9-inch and three 64-pdr. guns). By the end of the 19th century these had been replaced by four much more powerful guns: two 9.2-inch Mark X breech-loading guns and two 4.7-inch guns. The original thirteen emplacements were reduced to five by 1895. The fort continued in use during the Second World War and underwent further alterations when its two existing 6-inch close defence guns were enclosed within bomb-proof shelters. Fire control positions were also added, along with spigot mortars at each end of the terreplein. In 1956 the fort was decommissioned and sold to the local authority five years later, following which the surface buildings were demolished.[5]
To supplement the fort's firepower, two additional gun batteries were subsequently constructed nearby. These were Grain Wing Battery (constructed 1890–95) 50 metres (160 ft) south of Grain Fort, and Dummy Battery (constructed 1861–68), about 1 kilometre (0.62 mi) south of the fort. Neither was used for long before they were disarmed and used for other purposes, and both were decommissioned and sold off along with Grain Fort.[6]
Current status[edit]
Little is now visible of Grain Fort above the ground. In addition to the keep's demolition, the spaces within which the surface buildings once stood have been filled with rubble and rubbish. The fort's earthworks and a brick revetment still survive and a path links the concrete aprons of the infilled gun emplacements. The front caponiers are buried but have also survived mostly intact. Magazines and tunnels still exist within the subsurface structure and have been visited by urban explorers.[5] Many of the fittings are reported to still survive.[7] The site of the fort is now within the Isle of Grain Coastal Park, which is managed by the Friends of the Coastal Park in partnership with its owners, St James Parish Council.[8] The fort is part of a scheduled monument designated in 1976 to cover "coastal artillery defences on the Isle of Grain, immediately east and south east of Grain village".[7]
^ Wilson, J.D. (December 1963). "Later Nineteenth Century Defences of the Thames, including Grain Fort". Journal of the Society for Army Historical Research. XLI (168): 182.
^ Historic England. "Slough Fort and wing batteries (1021405)". National Heritage List for England. Retrieved 15 July 2015.
^ Saunders, Andrew; Smith, Victor (2001). "Grain Tower and Boom Defence – KD 96". Kent's Defence Heritage – Gazetteer Part One. Kent County Council.
^ Clements, W.H. (1998). Towers of Strength: Martello Towers Worldwide. Pen and Sword. p. 135. ISBN 978-0-85052-684-4.
^ a b c Saunders, Andrew; Smith, Victor (2001). "Grain Fort – KD 87". Kent's Defence Heritage – Gazetteer Part One. Kent County Council.
^ Saunders, Andrew; Smith, Victor (2001). "Grain Wing Battery – KD 94". Kent's Defence Heritage – Gazetteer Part One. Kent County Council.
^ a b Historic England. "Coastal artillery defences on the Isle of Grain, immediately east and south east of Grain village (1019955)". National Heritage List for England. Retrieved 13 July 2015.
^ "Isle of Grain Coastal Park". Friends of Grain Coastal Park. Retrieved 15 July 2015.
Hogg, Ian V (1974). Coast Defences of England and Wales 1856-1956. David & Charles. ISBN 0-7153 6353-0.
Historic England. "Grain Fort (418677)". PastScape.
Victorian Forts datasheet
Retrieved from "https://en.wikipedia.org/w/index.php?title=Grain_Fort&oldid=923110848"
Palmerston Forts
Forts in Medway
Forts on the River Thames
1861 establishments in England
Use British English from May 2017
This page was last edited on 26 October 2019, at 12:41 (UTC).


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Golazo Merchants: Wayne Rooney and 15 years of Premier League screamers
Liverpool defender Robertson looking forward to 'exciting' title race
Andy Robertson admits the Premier League title race is going to be 'exciting' after Liverpool moved to within a point of Manchester City with a 4-2 win over Burnley on Sunday.
Roberto Firmino and Sadio Mane both scored twice for Jurgen Klopp's side, as Liverpool closed the gap to leaders City back to a point after the Citizens beat Watford 3-1 on Saturday.
Speaking about the final eight games of the season, left-back Robertson said that it is going to be an 'exciting' climax to the campaign.
"It's another game down, eight to go. It's going to be exciting one way or another," Roberston told liverpoolfc.com.
"I've said in all the interviews I've done, we need to give 100 per cent in every single game and whether it gets us a trophy or it doesn't, we need to deal with that.
"The position we're in now, one point behind with eight games to go, if we perform like that – especially with our attitude – then it'll stand us in good stead.
"We've got some tough games coming up but we look forward to the chase and hopefully we can push them all the way."
Henderson admits Liverpool players are praying for a title race 'miracle'
in Opinion/Features
The role of narrative and history in Liverpool's quest to finally win the Premier League
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Klopp insists 'I'm not nervous' about title race
Andrew RobertsonLatest Liverpool newsLiverpoolManchester CityPremier League Title Race


ROADIE Canine Vehicle Restraint Training Harness Ruff Rider's award winning pet product "The Roadie" automobile safety harness for dogs is the best "Canine Seat Belt" available anywhere. Surpassing SAE standards for human seat belt tensile strength (5000 lbs. -Roadie 9300 lbs.). Designed with the help of a veterinary orthopedic surgeon, the ROADIE is orthopedically sound, ergonomically correct, and warranted for the life of your animal. Available in limited sizes in the original Basic and Elite models and now introducing the new Adjustable Model! Made in the USA.


Me and Miss salted cod are today reviewing one of the uni hangouts, the 4th floor café in the old building. A favourite among many because of its comfy chairs, old photos of 1920s LSE students and deli sandwich bar, it is arguably one of the best places for lunch on campus. But don't get carried away – that is in comparison with other uni outlets, which, in all honesty, hardly send us through the roof.
Their americano is decent and studently priced at 1.20 (admittedly 70p more than the canteen coffee, but I still feel a bit nauseous after having one of those yesterday) and the deli sandwich bar has a nice chicken tikka filling which, whilst on the pricier side, is nicer than anything we've so far tasted in the canteen opposite of the café. Remember to go for the speciality bread because the normal is disappointingly small.
The queue system is painstakingly slow as no one really knows how the ordering at the deli bar works, so avoid going here ten minutes after the end of any lunch time lecture. Their cakes always look inviting but beware: the lemon drizzle is nice and zesty but the coffee and walnut – for all it's glorious frosting – it's not very walnutty and too sweet. Massive minus for the fact that they chanrge you 20p for a glass of water. 4.5 meatballs out of 10.


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Q: Syntax Error: Invalid or Unexpected Token when running a nodejs file using Visual Studio Code (Using powershell) I've been trying to look for a solution but I can't seem to find one. I am a beginner to nodejs and basically I have created a new nodejs file called "app.js" inside of a directory called "HelloNode". When I use "node app.js" inside of powershell, the terminal tells me this:
This is the image of my screen
Code in VS Code:
var msg = "hello world";
console.log(msg);

Output in terminal:
PS C:\Users\yanab\HelloNode> node app.js
C:\Users\yanab\HelloNode\app.js:1
��v

SyntaxError: Invalid or unexpected token
    at wrapSafe (internal/modules/cjs/loader.js:1001:16)
    at Module._compile (internal/modules/cjs/loader.js:1049:27)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1114:10)
    at Module.load (internal/modules/cjs/loader.js:950:32)
    at Function.Module._load (internal/modules/cjs/loader.js:791:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:72:12)
    at internal/main/run_main_module.js:17:47

Solutions I have tried:

*

*Tried to change environment variable

*Used the nodejs correct version using nvm use 'version number'

Notes:

*

*Using a combination of Visual Studio Code and nvm

*After searching for a while it might have something to do with UTF-16 encoding and how it isn't in UTF-8 encoding but I may be wrong.

Solution:
Well I basically just made the file inside of vscode by right click -> new file and it worked. What I did before was use powershell and the command echo to make a new file. Don't understand what happened but making the file inside of vscode seems to be the solution.

A: I had the same situation. It turns out the file was UCS-2 encoded. After converting it to UTF-8 using notepad ++, it started working fine.
In my case, the reason for the UCS-2 encoding was the way I was filling out the file:
echo 'console.log("Hollow world");' > test.js

A: same problem here. I created file via powershell echo command. My solution is reopen my computer and create file without command line. :$

A: This is an error that appears when there is some enexpected syntax when running javascript.
at wrapSafe (internal/modules/cjs/loader.js:1001:16)
at Module._compile (internal/modules/cjs/loader.js:1049:27)

This second line says that this error appeared while compiling the code file. (even though javascript is not a compiled language). The same error appears for the following code(it wont even console log):
console.log('running code');
2q307qwekfjn;

So there is some error in the formatting of your file, some unexpected symbol(the ??v symbol) added by the ide or when saving etc.

A: The problem is with syntax, '' replace with '', usually few editors like the apple note program use ' instead of ' and when you copy-paste, it won't compile.

redpajama_set_name: RedPajamaStackExchange


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text:
Park, Hammig, and Jeong: Comparison of Characteristics of Gamma-Ray Imager Based on Coded Aperture by Varying the Thickness of the BGO Scintillator
Comparison of Characteristics of Gamma-Ray Imager Based on Coded Aperture by Varying the Thickness of the BGO Scintillator
Seoryeong Park1, 2, Mark D. Hammig3, Manhee Jeong4
1Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup, Korea
2Department of Environmental Engineering, Jeonbuk National University, Jeonju, Korea
3Department of Nuclear Engineering & Radiological Sciences, University of Michigan, Ann Arbor, MI, USA
4Department of Electrical and Energy Engineering, Jeju National University, Jeju, Korea
Corresponding author: Manhee Jeong, Department of Electrical and Energy Engineering, Jeju National University, 102 Jejudaehak-ro, Jeju 63243, Korea E-mail: mhjeong@jejunu.ac.kr
Received August 24, 2022 Revised October 06, 2022 Accepted November 06, 2022
The conventional cerium-doped Gd2Al2Ga3O12 (GAGG(Ce)) scintillator-based gamma-ray imager has a bulky detector, which can lead to incorrect positioning of the gamma-ray source if the shielding against background radiation is not appropriately designed. In addition, portability is important in complex environments such as inside nuclear power plants, yet existing gamma-ray imager based on a tungsten mask tends to be weighty and therefore difficult to handle. Motivated by the need to develop a system that is not sensitive to background radiation and is portable, we changed the material of the scintillator and the coded aperture.
The existing GAGG(Ce) was replaced with Bi4Ge3O12 (BGO), a scintillator with high gamma-ray detection efficiency but low energy resolution, and replaced the tungsten (W) used in the existing coded aperture with lead (Pb). Each BGO scintillator is pixelated with 144 elements (12×12), and each pixel has an area of 4 mm × 4 mm and the scintillator thickness ranges from 5 to 20 mm (5, 10, and 20 mm). A coded aperture consisting of Pb with a thickness of 20 mm was applied to the BGO scintillators of all thicknesses.
Spectroscopic characterization, imaging performance, and image quality evaluation revealed the 10 mm-thick BGO scintillators enabled the portable gamma-ray imager to deliver optimal performance. Although its performance is slightly inferior to that of existing GAGG(Ce)-based gamma-ray imager, the results confirmed that the manufacturing cost and the system's overall weight can be reduced.
Despite the spectral characteristics, imaging system performance, and image quality is slightly lower than that of GAGG(Ce), the results show that BGO scintillators are preferable for gamma-ray imaging systems in terms of cost and ease of deployment, and the proposed design is well worth applying to systems intended for use in areas that do not require high precision.
Keywords: Coded Aperture, Gamma-Ray Imaging, BGO Scintillator, Gamma-Ray Spectroscopy, Image Quality, Spatial Resolution
According to the International Atomic Energy Agency, 442 nuclear power plants were in operation worldwide as of March 2020, of which 296 were more than 30 years old, accounting for 66.9% of the total [1]. As the entire population of nuclear power plants ages and individually reaches the end of their operating life, research on the decontamination and decommissioning of nuclear power plants is underway. The two most important problems in decontamination, decommissioning, and demolition of waste classification are (1) nuclide identification and (2) accurate identification of the location of radioactive materials [2]. Furthermore, the capabilities to localize and identify radioactive materials are useful in environmental monitoring because monitoring demolition sites is expected to continue after a nuclear power plant has been decommissioned [3].
As a result, many research groups have successfully developed gamma-ray imaging systems that can detect the presence of radioactive materials. However, weighty equipment can make it difficult to effectively find hot spots contaminated with radioactive materials because the primary system of nuclear power plants has many pipes and pumps located in narrow spaces. Hence, reduction of the weight of the equipment to facilitate portability is an essential requirement.
Gamma-ray imagers are divided into two main categories, depending on the way in which the source image is obtained: Compton cameras and coded aperture-based imagers [4]. Typical Compton cameras include Polaris-H (H3D Inc., Ann Arbor, MI, USA) and HEMI (Lawrence Berkeley National Laboratory [LBNL]) whereas coded aperture-based gamma-ray imagers include iPIX (Mirion Technologies Inc., Atlanta, GA, USA) and HiSpect (CEA, Cedex, France) [5–8]. We developed a coded aperture-based gamma-ray imager named Epsilon-G (Energetic Particle Sensor for the Identification and Localization of Originating Nuclei-Gamma) and details of this design were reported previously [9].
The size and weight of Epsilon-G are 104 mm×144 mm× 197 mm and 5.7 kg, which exceed those of other gamma-ray imagers. Specifically, the aforementioned gamma-ray imagers weigh 4 kg (Polaris-H), 4 kg (HEMI), 2.5 kg (iPIX), and 3 kg (HiSpect), respectively. Because the Epsilon-G is designed to detect gamma rays in the energy range between 40 keV and 3 MeV, it uses a thick (2 cm) and dense coded aperture consisting of tungsten (W) with a purity of 99.5% and a density of 19.3 g/cm3 including a side shield encompassing the detector module for the detector module (scintillator and silicon photomultiplier [SiPM] array), which account for the bulk of the weight of the system. This prompted us to use a low-density material such as lead (Pb) instead of W to fabricate the coded aperture to minimize the total weight of the system.
Considering the high gamma-ray response efficiency and low-price competitiveness of bismuth germanate (BGO), we decided to evaluate the applicability of the imager by lowering the weight by replacing Cerium doped Gadolinium Aluminium Gallium Garnet, or GAGG(Ce), and changing the detector shielding structure. Many scintillators, such as NaI(Tl), CeBr3, SrI2(Eu), LaBr3(Ce), and LaCl3(Ce), have good energy resolution, but are particularly hygroscopic and the design is particularly difficult to pixelate, with low density and effective mass [10]. On the other hand, BGO has a lower photon yield than the GAGG(Ce) scintillator, but is neither hygroscopic nor does it have high density; thus, it can withstand a thinner active layer than GAGG(Ce) for imaging applications that do not rely on fine energy resolution for radioisotope identification. By reducing the thickness of the scintillator, the shield thickness of the coded opening side may be reduced accordingly, thereby reducing the weight and volume of the entire system.
In this study, we examined the spectral performance—energy resolution, peak-to-Compton ratio (PCR), and peak-to-valley ratio (PVR); the performance of the gamma-ray imaging system—angular resolution, field of view (FOV), and image sensitivity (IS); and the image quality—peak signal-to-noise ratio (PSNR), normalized mean square error (NMSE), and structure similarity (SSIM); while also determining the optimal scintillator thickness for the gamma-ray imaging system.
1. Epsilon-G
A SiPM has several features that improve the usability and robustness compared to conventional photomultiplier tubes (PMTs). It is capable of low-voltage operation (less than 50 V) and is insensitive to magnetic fields. The photodetection efficiency (PDE) of SiPM is generally higher than that of PMT, and the maximum PDE for recent SiPMs or multi-pixel photon counters (MPPCs) is approximately 50%, including the fill-factor loss [12]. Based on these characteristics, Epsilon-G, a coded aperture-based gamma-ray imager with pixelated GAGG(Ce) detector modules coupled to SiPM array, was developed [13]. The SiPM array (ArrayC-30035-144P; Semiconductor Components Industries, Phoenix, AZ, USA) used for Epsilon-G features high gain, low operating voltage, temperature stability, high output uniformity, and excellent single photon sensitivity at wavelengths ranging from ultraviolet to visible [14]. In addition, the GAGG(Ce) detector (Epic-Crystal Ltd., Kunshan, China) has high photon yield, fast decay time, excellent radiation resistance, and can be used under high-capacity conditions. As shown in Fig. 1, both SiPM and GAGG(Ce) arrays were pixelated into 12×12 elements, and the pixel sizes of SiPM and GAGG(Ce) were 3 mm×3 mm and 4 mm×4 mm, respectively. The pixel pitch of the scintillator and the SiPM array is 4.2 mm, and both were wrapped in Teflon tape to assist reflection and mitigate ambient light interference.
2. BGO Scintillator-Based Detector Module
The BGO scintillator emits green fluorescent light with a maximum peak wavelength of 480 nm and is widely used in high-energy physics, medicine, and geological research due to its high static force and proper flash efficiency [11]. As shown in Fig. 2, the BGO (Epic-Crystal, Ltd., China) is pixelated into 12×12 pixels, has a pixel pitch of 4.2 mm and a pixel area of 4 mm×4 mm, the same size as the GAGG(Ce) scintillator used in Epsilon-G. Between the respective pixels, a 0.2 mm-thick BaSO4 layer is coupled as a reflector, and the edge and bottom of the scintillator are wrapped in 0.3 mm-thick BaSO4 and aluminum foil. The BGO scintillator and SiPM array are optically coupled using an EJ-560 optical interface sheet (Eljen Technology, Sweetwater, TX, USA) and TSK-5353 optical grease (Momentive, Tokyo, Japan). The entire assembly containing the detector module was wrapped with Teflon tape. In Table 1, the scintillator characteristics of BGO are compared with those of GAGG(Ce).
3. Coded Aperture Design
A centered mosaic modified uniformly redundant arrays (MURA) pattern was used for the coded aperture mask that was employed to encode the spatial radiation-field information. A centered mosaic pattern is a method for obtaining a fully coded field-of-view (FCFOV) by copying and extending to (2p-1)×(2p-1) for the prime number (p) closest to the number of ranks of the detector [15]. The thickness of the optimal mask was determined to be 2 cm in a previous study [16] in terms of the PSNR, NMSE, full width at half maximum (FWHM), and SSIM. Therefore, in this study, a coded aperture mask that has a 21×21 mosaic MURA pattern with a thickness of 2 cm of Pb (density of 11.34 g/cm3) was used. As shown in Fig. 3, the thickness of the side shield for the detector module was manufactured differently depending on the thickness of the scintillator.
1. Comparison of the Spectral Characteristic
1) Energy resolution
Our previous work demonstrated that the spectral performance was excellent when the bias voltage of SiPM was 28 V, and based on this, the operating bias was set. The coded aperture mask was not used in experiments to measure the energy resolution. The activity of the source was 779.6307 kBq for 137Cs, located in the center of the FOV and 25 cm away from the detector. Since each pixel has a variable response, gain correction by pixel was performed as described before [15], and a spectrum was acquired by collecting 1,000,000 events for each different detector thickness, as shown in Fig. 4.
Fig. 4 shows the dependence of the 137Cs energy spectra on the thickness of the BGO scintillator and Table 2 compares the energy resolution (R), PCR, and PVR based on the thickness of the BGO scintillator. As indicated in the annotated information in Fig. 4, for the 10 mm-thick BGO scintillator, the resolution of the 662 keV peak was the best, and the PCR and PVR values were the highest. The change in thickness from 10 mm to 20 mm resulted in a minimal improvement in energy resolution, but the secondary escape of Compton scattering gamma rays was much higher for the 5 mm-thick BGO scintillator array, particularly for photons scattering forward after the initial interaction.
PCR and PVR measurements became less accurate as the thickness increased from 10 mm to 20 mm, although the maximum resolution decreased as the surface reflection and scintillator loss increased. To summarize, the 10 mm-thick BGO scintillator outperformed the 20 mm-thick BGO scintillator by 21%, 3.94%, and 9.81% in terms of the energy resolution, PCR, and PVR, respectively. Fig. 5, which compares the peak height for the different scintillators, shows that the relative height of the photo-peak increases as the thickness of the scintillator increases, which significantly improved the energy resolution of the BGO scintillator array with a thickness of 10 mm or more. The peak-to-total ratio refers to the proportion of the full energy peak portion of the entire set of spectral data and is used to determine the full energy peak efficiency. In terms of image sensitivity, the more the information corresponding to the full energy peak, the higher the image sensitivity of the system is. Concurrently, the larger the peak-to-total ratio of the energy spectrum, depending on the thickness of the scintillator, the higher the image sensitivity of the system becomes.
The light yield of the BGO scintillator is about 5.9 times lower than that of GAGG(Ce), requiring a readout system with a relatively large gain. In the case of BGO, a 5 mm-thick scintillator is sufficient to detect 662 keV gammas from 137Cs. As a result of the experiment, the peak channel values corresponding to 662 keV for each thickness decreased in the order of 5 mm, 10 mm, and 20 mm. However, as shown in Fig. 4, the detection efficiency of the secondary escape event increases because the capture volume increases as the scintillator thickness increases, which in turn increases PCR by reducing the Compton area across the entire spectrum. However, if the thickness of the scintillator is relatively long 20 mm, the high aspect ratio can lead to significant self-absorption due to several surface scattering events before the scintillator escapes the crystal, and the signal size can be relatively small as it is more likely to exit the used reflector to cause cross talk.
2) Comparison of spatial interaction distribution via 2D flood map
Using the data used for spectrum collection under the same experimental conditions as in the previous experiment, a two-dimensional (2D) flood map can be obtained by varying the thickness of the scintillator as shown in Fig. 6, which shows the interaction intensity for each pixel. The localization is the best, particularly near the center of the array, for the 10 mm-thick case. In the case of the 5 mm-thick scintillator, Compton events are the prominent reaction, as the thickness is not sufficient to absorb the 662 keV gammas from 137Cs used in the experiment. Consequently, the signal-to-noise ratio (SNR) of energy information used for determining the reaction position of the radiation becomes low, and the 2D flood map becomes relatively less well-resolved. In particular, this phenomenon is more pronounced at the corners. On the other hand, in the case of the 20 mm-thick scintillator, once the pixel ratio (i.e., area-to-height ratio) of the scintillator exceeds a certain level, the light self-absorption reaction occurs inside the scintillator and the reflective efficiency of the reflector decreases. This lowers the signal intensity because of information-carrier loss due to increased scintillator-light attenuation, which affects the positional resolution. Therefore, in the case of BGO, the scintillator array with a thickness of 10 mm was determined to have the appropriate pixel ratio for improved positional resolution.
To quantify these qualitative observations, a one-dimensional (1D) sum profile representing the sum of each column or row was used, as shown in Fig. 7, which shows that the overall count intensity is scaled according to the detected volume as expected. The edge pixels are not clearly separated, particularly for the 20 mm-thick scintillator because lower energy events are more predominant in the distribution. Regardless of the scintillator thickness, the pixels are not clearly separated from the response of their nearest neighbors because of the relatively low scintillation efficiency. This is attributed to the low light yield, resulting in the poor SNR in position extraction. The SNR is larger for the 10 mm-thick scintillator for which the signals have a greater number of information carriers. Thus, the positional resolution of this scintillator is superior to that of the others.
Owing to the reduced participation of multi-pixel events in the 10 mm-thick case, the FWHM of the pixel-peak identification is the smallest relative to the baseline (bottom of the peak in the middle position). In the case of the 5 mm-thick BGO scintillator, the relatively small thickness limits the degree of light spreading to a remarkable extent, but the resolution of the peaks near the edges does not improve because of signal loss owing to Compton scattering. In addition, in the case of the BGO with a thickness of 20 mm, the signals have to travel a relatively long distance, which can cause light to be generated and spread when reaching the SiPM. Therefore, in the case of scintillators with large densities and effective Z numbers such as BGO, the light reaching the SiPM spreads as the pixel length increases, thus the relative spatial resolution decreases, particularly near the edge. Therefore, the spatial resolution of the 10 mm-thick BGO, which has an appropriate length, is the highest.
The main factor affecting the spectral performance is the use of the BGO scintillator, whereas changing the shield from tungsten to lead affects the spectral performance negligibly. The reason for changing the shield from tungsten to low-density lead is to reduce the weight of the system. The same phenomena were observed for GAGG(Ce) scintillator-based systems.
2. Comparison of Imaging System Performance
1) Angular resolution
For the image used to evaluate the performance of the imaging system, all data obtained from the equipment were used instead of using a specific energy window or only data within full energy peak. The angle at which the two sources separated and began to appear was determined as the minimum value of the angular resolution, and the separation criteria were evaluated based on the 1D profile, as shown in Fig. 8. The precision of each resolution representing the separation of the two sources is determined by the number of ranks and spatial resolution of the mask. The spatial resolution is determined by the SNR of the signal by the row/column readout technique used in the signal processing circuit, which is determined by its noise level and the photon yield of the scintillator. The extent to which each resolution affected the thickness of the BGO was investigated as follows.
To test the angular resolution of the equipment, an image acquisition test was performed by increasing the distance between the two sources until two 137Cs point sources (300.606 kBq and 304.14 kBq, respectively) could be identified separately. At this point, the source-to-detector distance (SDD) was set to 1 m and 30,000 events were registered. Images were acquired by attaching a coded aperture mask to the front of the detector module, and the maximum likelihood expectation maximization (MLEM) method was used to reconstruct the image. At this point, the MLEM iteration number was set to 100. Quantitatively, the two sources were identified and visualized when the angles formed by the two sources and detectors were 9.5°, 8°, and 8.5° for BGO scintillators with a thicknesses of 5, 10, and 20 mm, respectively. An important factor in positioning gamma-ray reactions is the energy resolution of the detector. The higher the energy resolution, the more precise the positioning, thus the angular resolution is also affected. However, the angular resolution was approximately 1.2° lower than when using a 20 mm-thick GAGG(Ce) scintillator array because the photon yield was smaller than that of a GAGG(Ce) scintillator, resulting in a lower SNR in the signal processing circuit.
2) Field-of-view
In a gamma-ray imager, the FOV is the extent to which a source can be located by capturing a single photograph, and even gamma-ray sources at the same location require additional time to locate according to the FOV. The Compton camera does not have a limited FOV, but in the case of the coded aperture-based gamma-ray imager, the FOV is limited by the mask pattern, mask-to-detector distance, the spatial resolution of the detector, etc., owing to the structural characteristics. For this reason, the FOV is one of the performance indicators required for the gamma-ray imager, and in the case of iPIX and HiSpect mentioned earlier, the FOV is known to be 41.4°–48.8° and 35°, respectively [1].
In the FOV experiment, an image was acquired by increasing the angular deviation of the 137Cs point source that has an intensity of 604.746 kBq from the center of the scintillator. In addition, the image reconstruction condition, the number of counts recorded at each location, and the SSD were the same as in the previous angular resolution experiment. The results of the FOV experiment are shown in Fig. 9, and for the BGOs with thicknesses of 5 mm and 20 mm, the FOVs were 44.96° and 45.74° (41.4 cm and 42.2 cm at 1 m SDD), respectively, and in case of the 10 mm-thick BGO, the FOV was determined to be 49.96° (46.6 cm at 1 m SDD). In previous studies using 20 mm-thick GAGG(Ce), the FOV was 50°, and the reason for this difference is that the spatial resolution at the edge of the scintillator is lowered, as shown in Fig. 6, because of the lower energy resolution. Therefore, this shows that the spatial resolution performance must be excellent in order to maintain the own FOV of the system given.
3) Image sensitivity
The image sensitivity was defined as the minimum time taken to acquire an image at a given dose rate, and at this time, when the accuracy of positioning the source was 80% or more, it was determined as the minimum time. The image sensitivity measurements were conducted by setting the 137Cs dose rate as 0.03 μSv/h (the background dose rate was about 0.08 μSv/h). For the experimental environment, the SDD was set to 1.075 m, and the position of the source was placed at the center of the FOV. Similarly, a coded aperture mask was mounted on the front end of the imager to acquire an image, and the accuracy was confirmed by measuring the image reconstruction time ten times for each measurement while increasing the image reconstruction time by 1 second. The image reconstruction conditions were the same as those in the angular resolution measurement experiment.
The experimental results showed that the scintillator with a thickness of 5 mm needs 25 seconds for the dose rate of 0.03 μSv/h of 137Cs and requires 11 seconds with the scintillators with thicknesses of 10 mm and 20 mm, respectively. Fig. 10 shows an image of the graphical user interface (GUI) acquired using the BGO scintillator with a thickness of 10 mm. The image sensitivity was determined to vary depending on the thickness because the detection efficiency improves as the thickness of the scintillator increases. In addition, at the same dose rate, the image sensitivity did not differ significantly from that of GAGG(Ce) scintillators of the same thickness.
4) Image quality
Appropriate positioning of the source without image noise indicates the image reconstruction performance of a gamma-ray imager. In general, reconstructed radiographic images are evaluated by deriving the PSNR, NMSE, SSIM, etc. In this study, the image quality was evaluated by placing the 137Cs gamma ray source at the center of the FOV and 30,000 events were counted for the BGO of each thickness, as shown in Fig. 11. The image reconstruction conditions are the same as in the previous experiments. The results of each evaluation index of the reconstructed image are summarized in Table 3, and each index was derived as described before [19–21]. SSIM generated a reference image by computer simulation and was derived by comparing images reconstructed with data obtained experimentally. In general, the higher the PSNR, the smaller the NMSE, and the closer the value to 1, the higher the image quality of SSIM is determined to be.
The results of the image reconstruction experiments showed that the PSNR, NMSE, and SSIM results were the best for the 10 mm thickness. This is because an excessively thin scintillator decreases the probability of detecting incident gamma rays, whereas an overly thick scintillator decreases the image quality owing to count sharing between adjacent pixels, leading to noisy reconstructed images. Here, counting sharing refers to the mislocalization of pixels due to the light spread of the scintillator, which is the result of inaccurate positioning because of poor energy resolution. Ultimately, this means that the pixels become difficult to distinguish, as shown in Fig. 6C. If the pixels are not clearly separated and unclear data are used when creating the detector map, the probability of mislocalization increases when the image is reconstructed. Table 3 compares the image evaluation parameters of the BGO scintillators with different thicknesses with those of conventional GAGG(Ce) scintillator arrays.
The study reported in this paper was conducted to reduce the cost and weight of the existing Epsilon-G consisting of a gamma-ray sensor, a coded-aperture mask composed of W, and a data acquisition (DAQ) system, which is a combination of GAGG(Ce) and SiPM array. We replaced the mask material from W to Pb and scintillator medium from GAGG(Ce) with BGO, and selected the thickness of BGO to be used in the system. The performance of the detector was evaluated by comparing the spectral characteristics (energy resolution, 2D flood map and 1D row-sum profile) and imaging system performance (angular resolution, FOV, image sensitivity, and image quality) for BGO scintillators with three different thicknesses. The comparison of the spectral characteristics showed the energy resolution and spatial resolution were the highest for the 10 mm-thick scintillator. Finally, we confirmed that the image quality of the reconstructed images obtained with the system using the 10 mm-thick BGO scintillator was superior to that obtained with the other two BGO scintillators. Therefore, it was determined that the optimal BGO thickness for our system was 10 mm. In addition, the weight of the entire system with the Pb mask applied to the 10 mm-thick BGO was 4.6 kg, a reduction of approximately 20% compared to the existing GAGG(Ce) and W mask (5.7 kg). Compared with the results of previous studies of the GAGG(Ce) scintillator-based Epsilon-G, the system using the BGO scintillator with a thickness of 10 mm has energy resolution of 12.81%, angular resolution of 8°, FOV of 50°, and image sensitivity of 11 seconds at a dose rate of 0.03 μSv/h for 137Cs. This explains the poor photon yield of BGO relative to GAGG(Ce). However, considering the excellent affordability of BGO, we confirmed that it is well worth applying to systems intended for use in areas that do not require high precision.
This work is supported by Nuclear Safety Research Program through the Korea Foundation of Nuclear Safety (KoFONS) using the financial resource granted by the Nuclear Safety and Security Commission (NSSC) of the Republic of Korea (No. 2204019).
Conceptualization: Park S, Jeong M. Methodology: Park S. Jeong M. Formal analysis: Park S, Jeong M. Funding acquisition: Jeong M. Project administration: Jeong M. Visualization: Park S, Jeong M. Writing - original draft: Park S. Jeong M. Writing - review and editing: Hammig MD, Jeong M. Approval of final manuscript: all authors.
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(A) Epsilon-G, (B) 12×12 pixelated SiPM array, and (C) 12×12 pixelated GAGG(Ce) scintillator array. SiPM, silicon photomultiplier.
(Top) 12×12 pixelated BGO scintillators. The dimensions of each BGO are: (A) 50.8 mm×50.8 mm×5 mm, (B) 50.8 mm×50.8 mm× 10 mm, and (C) 50.8 mm×50.8 mm×20 mm. (D) Configuration of the detector including the scintillator, reflective index matching material, and SiPM arrays. BGO, bismuth germanate; SiPM, silicon photomultiplier.
(A) View of the coded aperture mask printed by a three-dimensional (3D) printer with pieces of Pb inserted. (B) Pb shields are inserted into the side of the scintillator, as follows: 5 mm (left), 10 mm (middle), and 20 mm (right). (C) Coded-aperture design for various scintillator thicknesses. In each coded aperture mask, the mask-to-detector distance is 4.2578 cm, and all pixels have the same size of 4.105 mm.
Cs-137 gamma-ray spectra acquired with the 50.8 mm× 50.8 mm×5 mm, 50.8 mm×50.8 mm×10 mm, and 50.8 mm× 50.8 mm×20 mm BGO scintillators coupled with 12×12 pixelated SiPM arrays. BGO, bismuth germanate; SiPM, silicon photomultiplier.
Comparison of the peak pulse height according to the scintillator thickness. The peak-to-total ratio was 25.91% for the 5 mm-thick volume, 37.52% for 10 mm, and 45.06% for 20 mm.
The 2D flood maps of (A) 50.8 mm×50.8 mm×5 mm, (B) 50.8 mm×50.8 mm×10 mm, and (C) 50.8 mm×50.8 mm×20 mm BGO scintillators coupled with 12×12 pixelated SiPM arrays. BGO, bismuth germanate; SiPM, silicon photomultiplier.
Normalized 1D row-sum profiles of the (A) 50.8 mm×50.8 mm×5 mm, (B) 50.8 mm×50.8 mm×10 mm, and (C) 50.8 mm×50.8 mm×20 mm BGO scintillators coupled with 12×12 pixelated SiPM arrays. BGO, bismuth germanate; SiPM, silicon photomultiplier.
Images showing the separation of the two sources for the BGO scintillator sized (A) 50.8 mm×50.8 mm×5 mm, (B) 50.8 mm×50.8 mm×10 mm, and (C) 50.8 mm×50.8 mm×20 mm (Top) and 1D profiles (Bottom). The angular resolution for each thickness of the BGO scintillator was 9.5°, 8°, and 8.5°, respectively. BGO, bismuth germanate.
Images acquired for each field-of-view (FOV) with a scintillator size of (A) 50.8 mm×50.8 mm×5 mm, (B) 50.8 mm×50.8 mm×10 mm, and (C) 50.8 mm×50.8 mm×20 mm.
Graphical user interface (GUI) image acquired by counting for 11 seconds at a dose rate of 0.03 μSv/h of 137Cs using the BGO scintillator sized 50.8 mm×50.8 mm×10 mm. BGO, bismuth germanate.
Reconstructed images for image quality evaluation. The size of the respective scintillators was (A) 50.8 mm×50.8 mm×5 mm, (B) 50.8 mm×50.8 mm×10 mm, and (C) 50.8 mm×50.8 mm×20 mm.
General properties of GAGG(Ce) and BGO scintillators
GAGG(Ce)
Density (g/cm3) 6.63 7.13
Effective Zeff (atomic) number 54.4 73
Wavelength of emission max (nm) 540 480
Primary decay time (ns) 88 317
Light output (photons/MeV) 50,000 8,500
Hygroscopic (Yes/No) No No
BGO, bismuth germanate.
GAGG(Ce), Cerium doped Gadolinium Aluminium Gallium Garnet.
Energy resolution (R), PCR, and PVR according to the thickness of the BGO scintillator
Energy resolution, R (%) 12.98 12.81 15.50
PCR 4.25 6.32 6.01
PVR 5.86 6.60 6.08
BGO, bismuth germanate; PCR, peak-to-Compton ratio; PVR, peak-to-valley ratio.
Summary of image reconstruction performance of the BGO with different thicknesses compared with that of GAGG(Ce) scintillator arrays
GAGG(Ce) [16,18]
5 mmt
10 mmt
FOV (°) 44.96 49.96 45.74 50
Angular resolution (°) 9.5 8 8.5 6.8
Image sensitivity (s) at 0.03 μSv/h of 137Cs 25 11 11 <2
PSNR (dB) 42.1561 47.2701 42.3702 66.93
NMSE 5.7084×10−5 1.8374×10−5 5.4501×10−5 8.07×10−7
SSIM 0.9958 0.9986 0.9836 0.9999
Weight (kg) 4.5 4.6 4.6 5.2
BGO, bismuth germanate; PSNR, peak signal-to-noise ratio; NMSE, normalized mean square error; SSIM, structure similarity.