Xeon
The first Xeon-branded processor was the Pentium II Xeon (code-named "Drake"). It was released in 1998, replacing the Pentium Pro in Intel's server lineup. The Pentium II Xeon was a ""Deschutes"" Pentium II (and shared the same product code: 80523) with a full-speed 512 kB, 1 MB, or 2 MB L2 cache. The L2 cache was implemented with custom 512 kB SRAMs developed by Intel. The number of SRAMs depended on the amount of cache. A 512 kB configuration required one SRAM, a 1 MB configuration: two SRAMs, and a 2 MB configuration: four SRAMs on both sides of the PCB. Each SRAM was a 12.90 mm by 17.23 mm (222.21 mm²) die fabricated in a 0.35 µm four-layer metal CMOS process and packaged in a cavity-down wire-bonded land grid array (LGA). The additional cache required a larger module and thus the Pentium II Xeon used a larger slot, Slot 2. It was supported by the 440GX dual-processor workstation chipset and the 450NX quad- or octo-processor chipset.
Enriched Xenon Observatory
In August 2011, EXO-200 was the first experiment to observe double beta decay of Xe, with a half life of 2.11×10 years. This is the slowest directly observed process. An improved half life of 2.165 ±0.016(stat) ±0.059(sys) × 10 years was published in 2014. EXO set a limit on neutrinoless beta decay of 1.6×10 years in 2012. A revised analysis of run 2 data with 100 kg·yr exposure, reported in the June issue of "Nature" reduced the limits on half-life to 1.1×10 yr, and mass to 450 meV. This was used to confirm the power of the design and validate the proposed expansion.