17:15 First Compton events with a Green Laser
seen!
See
Halog
entry 315776.
Signal to Background in Compton looks great, apparently. I hear numbers like 15 to 1. Jay's optics is working beautifully.
19:30 The R.C. asks me to request an escorted access for Compton work. I do so.
Access plans include a) Megan removing 1 cm diameter collimator on photon detector, and replacing it with the 2 cm diameter collimator, and also b) repositioning a camera; and c) Al and Abdurahim will be adjusting quarter-wave plate to balance the two helicity states in the cavity.
20:18 Access complete; ask for beam permit and then ask for 35 µA for more Compton data. Meanwhile, Bob Michaels called in for some expert-driven HRS studies.
20:50 We have had some 35 µA Compton data; Megan tells me to ask for 100 µA.
20:54 Beam has tripped off; MCC says they are getting trips in the injector at about 75 µA. Megan thinks we haven't been this high in current yet in this experiment? Ask them to go to 60 or 65 µA, wherever it is still happy with some headroom.
21:55 Beam has been off (they have had IOC that needed recovering). Meanwhile, I reboot the HRS IOCs (iochal4 and iochal6) and the septum IOC (iocha48), and set the "P0 SET" mode on both arms to PREX_B. All magnets come back happily, at "Tune B" settings, except I can't get Right Arm NMR to turn on, or respond to clicks on the "HMS RIGHT ARM DIPOLE NMR" GUI. So, I reboot by going to hareboot27, and then selecting port 8 (Right Dipole NMR). That works. Now, cycle Q2 on both arms (go to 1000 A, to 0 A, to 1000 A, to 0 A, then regulate), and cycle Q3 on both (up to 1400 A, then regulate).
22:10 Bob is now in; he calls for access to put in sieve slits. I turn off septum magnets as/per Jack Segal's halog entry to prepare for access.
Meanwhile, MCC calls to update us: they are calling an injector expert (Reza Kazimi). There has not been any delivered beam since it tripped around 20:54. Here is an Elog entry on injector optics problem.
22:35 Magnets are all (except septa) at PREX_B ("Tune B") settings, Q2 and Q3 on both arms have been cycled.
23:15 While waiting for beam, Alex C. and Megan F. go in access to the hall; Alex to replace a couple of chips on GEM, Megan to adjust Compton camera.
23:15 MCC calls; ask if we can have our people out in 15 minutes; I ask Alex, who is re-entering Hall with a box of GEM electronics parts, and he says yes, will tell Megan too... Beam may be imminent.
23:50 Megan, Alex out of the Hall; MCC ready to start tuning into our Hall. I Cycle the septa magnets up to 800 A, then set to P0 =1.063 in preparation for optics studies.
24:00 Shift ends.... Hand off to next crew.
Pedestals Parity LHRS RHRS Beam Current Run # Run # Run # (µA) ---- ---- ------ ------------ 2540 no target; during Compton studies 2541 " 2542 " 2543 " 2544 " no beam