Configurations of deflecting structures in TPS
The designed TPS ring is supposed to have six long straight (LS) and 18 short straight (SS) sections each 10.91 m and 5.31 m, respectively [9]. About one third of the ring is composed of straight lines accommodating special devices such as deflecting structures. Ten families of quadrupoles and eight families of sextupoles with mirror symmetry are employed in a superperiod. The main TPS parameters are given in Table 2. Fortunately, the vertical phase advance in each QBA lattice is about 2π which is in favour of the deflecting structures. Three alternative locations for placing the deflectors are designated in a super-period of TPS. To elucidate the effects of deflectors in each alternative location, five watch points are established in the system. Each watch point has the capability of monitoring the property/motion of the beam. As displayed schematically in Figure 3, the watch points are marked (W1) before the first cavity, (W2) after the first cavity, (W3) at the center of the undulator as the radiator, (W4) before the second cavity, and (W5) after the second cavity. All watch points are set on the coordinate mode [22] and in addition, a bunch of 10000 electrons with a Guassian distribution is tracked through each alternative configuration.

### Language ###
English

### Assessment ###
Could ask about the number of short straight sections in the TPS ring, which is clearly stated in the text.

### Query ###
How many short straight sections are there in the TPS ring?
How many short straight sections are there in the TPS ring?