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CHAPTER 12. POLARIZED 3 HE TARGET 188 In addition, there is a hazard associated with magnetic field. The maximum magnetic field is 35 Gauss inside the magnet. A warning sign will be posted around the target area. No person with pace maker will be allowed around the target area. The following personnel have received the proper training. They are the only ones authorized to operate the power supply and the magnets. Names may be added with authorization from the supervisor of the system (Jian-ping Chen, x7413). Name (first,last) Jian-Ping Chen Chiranjib Dutta Joe Katich Yi Qiang Vince Sulkosky Yi Zhang Dept. JLab Kentucky CWM Duke JLab Lanzhou Call [4] Tel Pager 7413 7413 5391 0012 5972 5635 5735 7254 5487 6166 0041 e-mail [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] Comment Contact Table 12.4: Polarized 3 He target: personnel authorized to operate the power supply and the target magnets Attached to the horizontal Helmholtz coils are two smaller sets of coils. These consist of 20 loops of 16 AWG wire attached to smaller DC power supplies. They can be used to compensate for field gradient to minimize AFP polarization loss. These coils can also be used to introduce a field gradient to reduce masing effect. 12.9 NMR Polarimetry This guide explains briefly how to perform safely an NMR AFP sweep on the polarized 3 He target. Figure. 12.8 shows the target setup and explaining the angle conventions of the polarized target system. 12.9.1 NMR polarization measurement An automatic NMR measurement will be performed every time the target spin gets flipped. Each of these measurement includes: • AFP flip of 3 He triggered by RF frequency sweep; • Laser polarization change by rotating Q-wave plates; • NMR data recording and automatic polarization calculation; • Spin state determination; • Automatic log entry. For a manual NMR measurement, it has the following steps:
