Here is an update of the g2p|gep experiment status.
On Monday(Apr 2) afternoon there is a fire alarm happened in Hall A due to the failure of the dehumidifier of hall A dump. After replacing some parts, it is now working well.
On Tuesday there was a 10-hour beam study. Hall A is in controlled access. During this access, the following problem are solved or diagnosed: 1) Left BCM signal can be seen after replace a bad NIM to BNC converter. The copy module also got swapped. 2) High T2 rate issue, but not fully understood yet 3) Slow raster signal was connected to the 3rd arm DAQ to monitor beam spot. Coda updated and it works fine 4) Right dipole was reset. We can control the current remotely now. 5) Right septum current was test to 850A. The limit for septum current now has been changed to 850A. 6) Right sieve slit shaft has been check, nothing wrong with it. 7) Hall A dump dehumidifier is fixed. 8) Harps were not working, Anthony checked the hardware. he said that the hardware is ok. Yves suggested to check|replace the amplifier. But we did not manage to do that before closing the hall.
After recover the beam, the 2nd half of optics for 2.5T, 90deg 2.254GeV was carried out. We then return to the 2nd pass of the production.
Wednesday(Apr 3), we continue to take production data. In the morning we found that the 3rd arm saw 9kHz trigger rate at 50 nA beam (1.5kHz@50nA is normal). We found that the beam scratch the beam pipe upstream of the target. After playing with beam position and the slow raster size, the rate drop to 4.X kHz. It still scratch somewhere further up stream, but we don't know where. We also found that if hall c is not running, our beam energy starts to drift away. The beam polarization should also be calibrated for these case. This should be taken care during data analysis.
A controlled access was requested to taking care of the harps. The amplifier were replaced but no luck to get them work. We will try to loot at them again tomorrow.
We are taking production data without harps. The spot++ result shows that the beam still scratch something in the beam pipe (check http://hallaweb.jlab.org/halog/log/html/1204_archive/120404193302.html and http://hallaweb.jlab.org/halog/log/html/1204_archive/120404202257.html). We will take a deep look at it once the harps are ready.
Tomorrow(Apr 5) we will do anneal at 3PM for 2 hours. We will open the hall as controlled access. If anyone want to access the hall, please inform the RC.
-- Best Regards, Jixie Zhang Hall A Run Coordinator 876-1787 _______________________________________________