The E89-003 experiement has finally started last night, 18th of May, 1997. After a long and pain struggling of solving all the problems in the hall, we were finally able to close the hall at 10pm, about one minute before the MCC's ultimatum: either close the hall at 10:00pm or not going to receive the beam till late Tuesday. After several hours of tuning the beam, the accelerator people managed to delived the beam simultaneously to three halls. Hall A received the CW beam around 3:40am. It has been a long and exhausting weekend for us, epecially for the Hall A technicians and engineers. Javier, James and Mark were trying to get the spectrometers ready for the experiment, Ed had attempted several times to fix the leak on the exit window of the spectrometer, when the waterfall target window ruptured. After putting the 1mil stain-less steel window for the target, we obtained the cooperation from CEBAF survey group who agreed to work for us on Saturday. They surved the target outside the chamber at first, then put the target in the scattering chamber and surveyed again. The solid target and the old waterfall target was tilted initially, so we decided to put the waterfall target at exactly zero degree this time. The work finished about 4pm Saturday, but when Ed put the scattering chamber window back, they found a leak. So they have to redo the chamber window and resumed the work on Sunday. It went smoothly on Sunday till early afternoon, when we found the target vacuum doesn't go down and the MCC was chasing us to give a definite answer when we are going to be ready. At around 8pm, we still hadn't got the vacuum we need, Jack and Mark tried their last attemp: heating the bottom of the target chamber with two fans! And it had worked! Meanwhile, Javier and James had finished their check of the circuit of the magnets and finally got the paper signed off. The run plan right now is to start with the target thickness measurement, then the magnet reproducibility, then access to the hall to switch the polarity of H-arm for proton, set the magnet for H(e,e'p), do a quick measurement to get absolute cross section and then start the production run. Right now we are still in the middle of target thickness measurement. The owl shift had decided themselves to start with BCM calibration with waterfall target at more than 60 microA, a very brave attempt (since we had never seen the beam in hall A more than 50 microA yet), which failed due to high radiation level in the hall. Then they went back to the run plan, did the BeO measurement. After they finished and want to switch back to waterfall target to measure H2O, Hall C refused to let them stop the beam to move the target. After I talked to Hall C after the 8am meeting, they agreed to let us move the target. Since we have already lost about 2 days official beam time, and given the complicated situation of running in three halls (conflit in changing beam condition, access etc.), I have to ask you all strictly follow the run plan to minimize the unnessary lost of beam time. Arun had talked to the RadCon people and they have agreed to raise the radiation level threshold in the hall. Right now we are running at about 10-20 microA with waterfall target, and can run with this current till we finish the target thickness and magnet reproducibility checking. Then when we are asking for the access to the hall to change the polarity of H-arm, we will ask RadCon people to change the radiation threshold at the same time. Hopefully we can get this done by late today, so we don't have to wake Mark Stevens in the middle of the night to change the polarity for us. Meme The current status in the hall is that we haven't seen the beam since yesterday noon time. Accelerator has problem with injector, none of the three halls has got any beam. As for our program, we are still at beginning of the run plan, have not finished the target thickness measurement. Nilanga and the people on shift found that the data we took had very bad momentum resolution. There was suspection that the Quadrupoles might have different offset in current than before. John LeRose had checked all the settings and the conclusion is that it should not due to the quads. Bob had mentioned that Tom Hassler has seen a peak to peak 1mm 60 Hz signal from their fast EPICS data. This will for sure affect our momentum resolution. When I talked to Jay Benesch, he mentioned that they have had this 60 Hz problem all the time, except we didn't see that signal that big before. It's not clear to them what may be the cause but he suggested that once we got the beam, we should try to switch the BPM lock off and taking data for about half an hour to see whether the BPM itself has caused the problem. Javier found out this morning that the protecting plastic window for the scattering chamber was still there, which, if I remebered it correctly, had been put back for protection when people were trying to pump down and heating the base of the chamber up, and we forgot to take it out when closing the hall. Since we were not far in the program (only got data on BeO), I have decided to redo the whole thing again, once the beam is back. Since there is the controlled access in the halls, we have asked the RadCon people to raise the radiation level threshold in the hall. The threshold was set at 0.7 krads, and they raised it to 4 krads now, which should be able to handle 70 microA current we are going to use. Meme The day shift yesterday didn't see any CW beam. MCC was working hard to restore the beam to three halls. While the machine was down, Ed Folts took a controlled access and remove the protecting window of the scattering chamber. Later, people on shift had taken some data to check the momentum resolution, which is about 4*10^-4, close to what we are expecting for. At about 8pm, beam was delivered to three halls and we start to take data with BeO. Till 8am this morning, we had about 6 hours data taking, and the target thickness measurement finished at about 9am. Right now people on the shift are set the magnet back to initial value, after set B=0, and wait for the beam to come back at about 11am. I have just been told that MCC took the beam down to fix some problem in the injector. Once the beam come back, we will take another 1-2 hours data and then ask for the access to the hall to change the polarity of the H-arm. Since the beam energy measuremnts (arc and (e,p) measurements as Larry Cardman suggested) are not available at this stage, we will rely on the information from BPMs along the beam line, which shall be able to provide us the relative stability of the energy. Jay Benesch (the program deputy) agreed to look into the possibility of getting dp/p information from the BPM, and we will check the BPM information taken in our data stream too. After the magnet reproducibility is done, we will continue with the efficiency calibration till noon May 23. The CEBAF management has allocated us several days extra beam time, starting from May 30th, 16:00 till June 5th, 8:00 for the 845 MeV program. So we will do the production run in that period. This will also save us some time for doing the q-value check with sieve slit. Meme The first party of the run plan, target thickness and the magnet reproducibility was finished at about 4:30pm. The availability of the beam was still very low, with all three halls waitting for the beam most of the time. At around 5:30pm, Hall C finally let us take the long scheduled access to the hall to switch the polarity of the H-arm. Meanwhile there was suspection that there might be a loose wire hang around somewhere around Q1 and Q2 on H-arm, which might be the cause of a mystery half empty ring in the theta_tg vs. phi_tg reconstruction. Checked the old commisioning data, which also pointed to prior dipole possibility. So we decided to open collimator on H-arm to check. A loose NMR wire was hanging around between Q2 and dipole. This is fixed now. Sirish and his Moller collaborators also took the chance to check their Moller polarimeter. During the access John LeRose and Mark Stevens had realize the abnormal behavior of Q1 and the He level was dropping. When consulting MCC, they realized that End Station Refrigerator crashed. It took them about 2 hours to restore the ESR, meanwhile the "warm" He gas was still flowing which effectively warmed up our liquid He for Quadrupols and Dipoles!! The dipole He level dropped to about 10%. After the Cryogenic group restored ESR and refilled the LHe to the magnets, the E-arm dipole was reset by 11pm. H-arm dipole was reseted later, but tripped several times. The display showed that the He flow rate was too high, which tripped the interlock. This kept going on till about 1am. The owl shift called Mark Stevens in and he suggested to have an access to reduce the He flow so at least H-dipole can be kept stable. They took the access but around that time the display for H-arm magnets were all blanck. They had tried varies ways of resetting without success. Around 5am, they decided go ahead with the white spectra measurement of quasielastic 16O(e,e') with E-arm. They did one BCM calibration and finished 5 delta scan at around 8am. This morning Javier and James were spending the most morning trying to fix the H-arm magnets. The message was that the IOC crashed caused by switching off the NMR power supply or glitching caused NMR power and improper procedure to reestablish the connection. Both spectrometers are ready right now for taking beam, but MCC is again struggling of sending us the beam. Also last night, we didn't get more than 50 microA due to some beam loss when tunning three halls. But we were pretty happy of operating at about 45 microA with prescale factor 1. When the beam comes back, we will continue the white spectra on H-arm (16O(e,p)), 5 delta scan, with E-arm running parasitically for three of the five delta scan for cross check. There are two delta scan for E-arm which need to be remeasured since there were some problems with Q2 settings. These two settings will run parallel with H-arm with the same prescale factors. Since the last update, we had taken about 6 hours data, mostly during the evening shift. Due to some anticoincidences between the accelerator and our magnets, we did not have the full usage of the already very limited (availability) beam. Right now, we are about two delta scan away from finishing the white spectra, for which we need about 2 hours data taking. The accelerator is scheduled to shut down at noon, and right now they are still tunning the beam ... Let's see how far we can go ... FINALLY we have finished the white spectra measurement. The accelerator started to deliver the stable CW beam to hall A shortly before 11am, and was kind enough to grant our request to extend the beam till 12:30. By that time Hall A was the only hall receiving beam (thanks to T20 allowing us to finish our plan), and MCC had suggested to increase the beam current to 60 microA to help us speeding up the data taking. This was actually the highest current on target ever seen in Hall A. The data taking stopped at 12:25. Sirish took the rest 5 minutes and managed to get MCC to give him another 5 minutes to do his Moller target test. The target was in 2 microA beam for about 4 minutes and survived. The Hall is opened now. We will start our program again on May 30th, 16:00. Have a good holiday, Meme Upto now, 2 June 15:30, we have taken about 20 hours data. The MCC started to deliver the stable usable beam around 5pm yesterday, and we have had very good use of it !! Our program started with some quick check of dead time and data acquisation rate affected by prescale factor while John LeRose and his team from parity group were evaluating the beam quality. This check settled our long discussions of which dead time we are going to run for the H(e,e'), H(e,p), H(e,e'p) calibration. The results showed that at about 30% dead time, the data acquisation rate was about 300 Hz, about 90% of the maximum rate we can run with current CODA. Meanwhile, Geraud Laveissiere was called in to perform the BCM calibration with beam current at 70 microA. We can run the calibration now ourself without interrupting the other halls. We are going to do this calibration at least once a day while we are changing the magnets. After the three halls finished the evaluation, we started to do the second part of the efficiency calibration: the delta scan of H(e,e'), H(e,p) and H(e,e'p) on both spectrometers. This is to measure both the absolute cross sections of H(e,e'), H(e,p) and H(e,e'p) and the efficiences of electron and proton. The swing shift and owl shift had finished the delta scan on E-arm, and right now we are in the middle of the delta scan on H-arm. Since we would like to take the data with prescale factor of 1, the high proton single rate forces us to run at very low current, we decided to break each run into two runs: one with prescale factor one for electron, proton singles and coincidence at very low current (e.g. 2 microA), taking data mainly for proton singles to get the cross-section of H(e,p); then prescale proton single rates such that it doesn't affect the electron single and coincidence data taking, and increase the beam current (e.g. 40 microA), which shall enable us to get the H(e,e'), H(e,e'p) absolute cross-section and proton efficiency from H(e,e'p)/H(e,e') faster. If the beam keeps stable as it is so far, we should be able to finish the delta scan on H-arm by midnight today. The production run will start once we finish the efficiency calibration. The items on the current run plan: 1) sieve slit run to check the q-value; 2) production run for current spectrometer settings, i.e. theta_pq=0^o; 3) move H-arm to theta_pq=8^o, survey, then production run; 4) move H-arm to theta_pq=16^o, survey, then production run. The other two angles theta_pq=20^o and 12^o will be decided later according to progress. During the meeting last Wednesday morning, we all agreed that we will finish the 845 MeV kinematics before we start to move on to 1.6 GeV or 2.4 GeV. The 1.6 GeV program was initially scheduled to start on June 6, and we will continue into that block of beam time should we haven't finished the 845 MeV data by June 6. What we are going to do then will depend on how much beam time and which beam energy are available: 1.6 GeV or 2.4 GeV. Meme It's been two days since my last update. Larry Cardman's strategy of giving MCC enough time to fix their problem certainly succeded. So far, the beam availability was very good. In principle MCC was able to deliver the beam all the time, with our requirement of beam intensity and beam position. A lot of things had happend during these two days. First and the most important: We have finished the efficiency calibration yesterday, and started at 5am the first thing in our production run list---the q-vector measurement with sieve slit. We had accummalated about 500 events in the central hole and central foil by 11am and decided good enough for determining the q-value. Then at yesterday noon time, we started the first real long-waitted production run at theta_pq=0^o. We were running at 70 microA, and the rate in p_1/2 state is about a factor 2/3 of the rate estimated from PWIA. We had assumed the real world might be a factor 3 off from the estimation, so the real data were taken faster than we expected for the worst case. This has certainly been our life saver, because the waterfall target was causing problem again around 10pm last night. By that time we had sampled about 2.5k events in the p1/2 state. The problem occured when Hall C was doing their beam energy measurement (during which we can't take data). The scattering chamber vacuum dropped which closed the beam line volves. Closer investigation showed that the O-ring (it was rubber) between the Be-window and target cell of waterfall target was leaking. Since the chamber was very hot, the Hall A technicians had to wait till it cooled down and then open the scattering chamber and to fix the problem. This has caused us about 2 shifts beam time so far. We didn't find any drawings for the o-ring. The decision now is to use In O-ring this time. By 5pm today, the hall is closed and is ready to take beam. While the hall was open during the day, we decided to move on to the next program: move the spectrometer to the setting for theta_pq=8^o and surveyed the spectrometer. The CEBAF servey group had provided one person to help along. The hope right now is that if the rate is better than our estimations, and we get enough beam time, we might be able to move the spectrometer for the theta_pq=16^o setting late tonight, and then we will take as long as needed to finish that point. As it is planned, also since I am going to be out of town for few days, Kevin will take over the all loads as a run coordinator tomorrow 8am. You will hear more from him then. Thank you all for the help and patients, Meme Dear Colleagues, FLASH: We have seen what we believe is the 'sd' state of 16O at theta_pq = 8deg with our quasi-online data analysis. Update for 970605: 00.00 - 10.00: 0.845 GeV, theta_pq = 16deg 10.00 - 14.00: break for accelerator 14.00 - 20.30: survey 20.30 - 21.30: sweep; lockup; tune 22.00 - 0.845 GeV, theta_pq = 16deg (continue) We began the day data taking and got a good chunk of our runtime at our largest pmiss at this beam energy on the books. This was followed by a shutdown for accelerator to setup the other Halls, as well as our 1.645 GeV measurement (which we hope will begin tomorrow). The downtime was spent surveying with the help of the pros. There is definitely a learning curve for us. We will be back online by 22.00, and plan to finish our data taking at 0.845 GeV overnight. Regards, Kevin ######################################################### # K.G. Fissum phone: (757) 269 7325 # # MS 16B, Room 16-125 fax: (757) 269 6273 # # Jefferson Laboratory pager: (757) 680 2036 # # 12000 Jefferson Avenue # # Newport News, VA 23606 USA # ######################################################### Dear Colleagues, Update for 970606: 00.00 - 10.00: 0.845 GeV, theta_pq = 16deg 10.00 - 18.00: HRSe & HRSh angle change & survey 18.00 - 19.00: checklist & reenable systems 19.00 - 20.00: sweep; lockup 20.00 - : Sirish & Moeller: 1 hour program 22.00 - (?) : begin 1.645 GeV program, white spectra... We began the day data taking and completed our runtime at the largest pmiss at 0.845 GeV, thus ending our program at the first beam energy. This was followed by an access to move to our first set of angles for 1.645 GeV. HRSh was moved and surveyed easily. HRSe lost a drive motor. This caused some delays, but nothing major. The survey of HRSe will have to wait for the June 10/11 shutdown. We have locked up now, and Sirish will do some tests of the Moeller for an hour or so. After this, we will commence with our white spectra program at the new beam energy. Regards, Kevin ######################################################### # K.G. Fissum phone: (757) 269 7325 # # MS 16B, Room 16-125 fax: (757) 269 6273 # # Jefferson Laboratory pager: (757) 680 2036 # # 12000 Jefferson Avenue # # Newport News, VA 23606 USA # ######################################################### Dear Colleagues, Update for 970607: 00.00 - 05.00: completed white spectra 05.00 - 10.00: HRSe H calibration program 10.00 - 12.00: checklist & reenable systems 12.00 - 13.00: sieve slits to check specs 13.00 - 19.00: HRSe H calibration program 19.00 - (?) : HRSh H calibration program... We began the day by completing the white spectra program at 1.645 GeV. Somewhere into the HRSe H calibration program a question about the polarities of the various quads arose and had to be addressed. It was. By 13.00 we were back online, and by 19.00 we were onto the HRSh H calibration program. Next comes q... Regards, Kevin ######################################################### # K.G. Fissum phone: (757) 269 7325 # # MS 16B, Room 16-125 fax: (757) 269 6273 # # Jefferson Laboratory pager: (757) 680 2036 # # 12000 Jefferson Avenue # # Newport News, VA 23606 USA # ######################################################### Dear Colleagues, Update for 970608: 00.00 - 03.00: HRSh H calibration program 03.00 - 04.30: q determination 04.30 - 10.00: 1.645 GeV, theta_pq = 0deg 10.00 - 16.30: move HRSh and survey 16.30 - 18.30: checklist, sweep, lockup, tuneup 18.30 - 22.15: 1.645 GeV, theta_pq = +8deg 16O 22.15 - (?) : 1.645 GeV, theta_pq = +8deg 12C We began the day by completing the HRSh calibration program and determining q. Upon completing the theta_pq = 0deg measurement, we accessed to move HRSh to theta_pq = +8deg and survey. By 22.00, we expect to have this point done. We are well ahead of schedule and have decided to do an R_lt on 12C in these kinematics to take up some of the slack. Regards, Kevin ######################################################### # K.G. Fissum phone: (757) 269 7325 # # MS 16B, Room 16-125 fax: (757) 269 6273 # # Jefferson Laboratory pager: (757) 680 2036 # # 12000 Jefferson Avenue # # Newport News, VA 23606 USA # ######################################################### Dear Colleagues, Update for 970609: 00.00 - 03.00: recover from H2Ofall and controls burps 03.00 - 09.30: 1.645 GeV, theta_pq = -8deg 16O 09.30 - 10.15: y/i study 10.15 - 13.30: machine development 13.30 - (?) : 1.645 GeV, // dip kinematics Emiss study Last night's poke at a 12C R_lt failed with the waterfall target controls, so the night was spent finishing up the theta_pq = -8deg point. After some y/i studies and machine development time, we find ourselves in the fortunate position of having 18 hours of "found" time. We have decided to spend it on a dip region parallel kinematics Emiss investigation of 16O. Regards, Kevin ######################################################### # K.G. Fissum phone: (757) 269 7325 # # MS 16B, Room 16-125 fax: (757) 269 6273 # # Jefferson Laboratory pager: (757) 680 2036 # # 12000 Jefferson Avenue # # Newport News, VA 23606 USA # ######################################################### Dear Colleagues, Update for 970610: 00.00 - 07.00: 1.645 GeV, // dip kinematics Emiss study 07.00 - (?) : ACCESS We finished using the "found" beam time on the parallel kinematics dip region Emiss study. After gaining entry to the Hall, the HRSe was surveyed and then moved to its 2.445 GeV position. The waterfall target has been removed to replace the existing gaskets with Indium. The day ended with a survey of HRSh. We are on track for lockup. Regards, Kevin ######################################################### # K.G. Fissum phone: (757) 269 7325 # # MS 16B, Room 16-125 fax: (757) 269 6273 # # Jefferson Laboratory pager: (757) 680 2036 # # 12000 Jefferson Avenue # # Newport News, VA 23606 USA # ######################################################### Dear Colleagues, Update for 970611: 00.00 - (?) : ACCESS As of 18.30: HRSe was surveyed in its correct position. The waterfall target was re-installed, and is good to go. Pins are used to locate it so a resurvey was not necessary. HRSh was surveyed, repointed and surveyed again. It is good to go as well. The detectors have all been checked out, and the lockup checklist performed. The magnets are all set. We are waiting on some last minute Moeller details before closing the huts, sweeping and eventually going to beam permit. 2.445 GeV beam will be brought into the Hall tonight (with any luck). Regards, Kevin ######################################################### # K.G. Fissum phone: (757) 269 7325 # # MS 16B, Room 16-125 fax: (757) 269 6273 # # Jefferson Laboratory pager: (757) 680 2036 # # 12000 Jefferson Avenue # # Newport News, VA 23606 USA # ######################################################### Dear Colleagues, Update for 970612: 00.00 - 08.30: tuning 08.30 - 15.00: some pulsed, some CW, insufficient quality 15.00 - 17.00: more tuning 17.00 - (?) : FPP unpolarised Today has been spent trying to bring the machine back up at 2.445 GeV after the 2-day maintenance period. The first tuning period resulted in an unacceptable beamspot in Hall A, resulting in a second tuning period. The Moeller folks have used the pulsed beam to their advantage, and will continue to piggyback other efforts well into this run period. It is projected we will come up with acceptable quality high current unpolarised beam at 17.00 this afternoon, at which point the FPP people will begin a long test run to last until well into tomorrow morning. Regards, Kevin ######################################################### # K.G. Fissum phone: (757) 269 7325 # # MS 16B, Room 16-125 fax: (757) 269 6273 # # Jefferson Laboratory pager: (757) 680 2036 # # 12000 Jefferson Avenue # # Newport News, VA 23606 USA # ######################################################### Dear Colleagues, Update for 970613: 00.00 - 04.00: poor quality beam "used" by FPP 04.00 - 15.30: accelerator installations 15.30 - (?) : lockup and tuning The day began with poor quality beam to Hall A which was used by the FPP. Nothing much was accomplished. At 04.00 the beam was discontinued for an accelerator installation period. This period ended about 15.30, and lockup is underway. After a tuning period of length "to be determined", we will begin with the white spectra program of E89003. Interwoven amongst these measurements will be some Moeller tests. FPP has deferred their request for beam. Regards, Kevin ######################################################### # K.G. Fissum phone: (757) 269 7325 # # MS 16B, Room 16-125 fax: (757) 269 6273 # # Jefferson Laboratory pager: (757) 680 2036 # # 12000 Jefferson Avenue # # Newport News, VA 23606 USA # ######################################################### Dear Colleagues, Update for 970614: 00.00 - 15.00: accelerator installations 15.00 - 21.00: tuneup 21.00 - (?) : Moeller woes Hurry up and wait! Today has been another long day. Accelerator had a lot of trouble with short circuits during the installation of the extra magnet required for 5-pass beam to Hall B. After that, there has been a lot of trouble with the Moeller quads - first the absolute settings, and then obtaining the absolute settings. No one seems to know. Kevin ######################################################### # K.G. Fissum phone: (757) 269 7325 # # MS 16B, Room 16-125 fax: (757) 269 6273 # # Jefferson Laboratory pager: (757) 680 2036 # # 12000 Jefferson Avenue # # Newport News, VA 23606 USA # ######################################################### Dear Colleagues, Update for 970615: 00.00 - 05.30: accelerator tuneup 05.30 - 10.00: white spectra/Moeller tests 10.00 - 11.00: system checks 11.00 - 11.30: current calibration 11.30 - 12.30: white spectra 12.30 - 17.00: no acquisition - pulsed beam only 17.00 - 19.30: more system checks and tuning 19.30 - (?) : continue white spectra Another long day, but things are improving. The white spectra measurements are nearing completion, after which the H calibration program begins. No major changes to the accelerator are forecast for the next week or so, so I expect the operational conditions to get better and better. Kevin ######################################################### # K.G. Fissum phone: (757) 269 7325 # # MS 16B, Room 16-125 fax: (757) 269 6273 # # Jefferson Laboratory pager: (757) 680 2036 # # 12000 Jefferson Avenue # # Newport News, VA 23606 USA # ######################################################### Dear Colleagues, Update for 970618: 00.00 - 10.00: H(e,e'p) calibration 10.00 - 24.00: no useable beam I am afraid yesterday was another tough day. We got a couple more of the delta scan points done before the accelerator failed, and despite their best efforts, they couldn't provide anything useable for the remainder of the day. Kevin ######################################################### # K.G. Fissum phone: (757) 269 7325 # # MS 16B, Room 16-125 fax: (757) 269 6273 # # Jefferson Laboratory pager: (757) 680 2036 # # 12000 Jefferson Avenue # # Newport News, VA 23606 USA # ######################################################### Dear Colleagues, Update for 970619: 00.00 - 04.00: no useable beam 04.00 - 12.00: restricted access 12.00 - 18.00: controlled access 18.00 - 24.00: waiting... Yesterday was again a tough day. Accelerator was unable to deliver anything of any use to Hall A for a 24-hour period. Kevin ######################################################### # K.G. Fissum phone: (757) 269 7325 # # MS 16B, Room 16-125 fax: (757) 269 6273 # # Jefferson Laboratory pager: (757) 680 2036 # # 12000 Jefferson Avenue # # Newport News, VA 23606 USA # ######################################################### Dear Colleagues, Update for 970620: 00.00 - 01.30: no useable beam 01.30 - 03.30: H(e,e'p) calibrations 03.30 - 06.00: no useable beam 06.00 - 09.00: H(e,e'p) calibrations 09.00 - 13.30: no useable beam 13.30 - 14.00: q determination 14.00 - 15.00: theta_pq = 0 15.00 - 19.45: recover from HRS2 dipole dump 19.45 - 20.00: remeasure q 20.00 - (?) : theta_pq = 0 Back on track? Today we finished (finally!) the H(e,e'p) calibrations and proceded onto the q vector determination. We got as far as an hour into our theta_pq = 0 run before we lost the HRS2 dipoles to what we believe is our daily power brown. After recovering, we remeasured q and happily found it to be the same as before the dump, and continued on the theta_pq = 0 run. This leaves us with an angle change to theta_pq = -16deg to occur at about 23.30. Kevin ######################################################### # K.G. Fissum phone: (757) 269 7325 # # MS 16B, Room 16-125 fax: (757) 269 6273 # # Jefferson Laboratory pager: (757) 680 2036 # # 12000 Jefferson Avenue # # Newport News, VA 23606 USA # ######################################################### Dear Colleagues, Update for 970621: 00.00 - 02.30: move HRSh to theta_pq = -16deg 02.30 - 04.00: tuning to Hall B 04.00 - 06.00: HRSh Q1 troubles 06.00 - 11.00: no useable beam 11.00 - 24.00: 2.445 GeV, theta_pq = -16deg At 00.00 the HRSh was moved to the theta_pq = -16deg. An uplugged VME crate caused a lot of trouble. After tuning losses and HRSh Q1 faults, we finally got on the air about 11.00 yesterday. Our event rate is *substantially* lower than what we expected from the Monte Carlos. That said, the data look very nice. Kevin ######################################################### # K.G. Fissum phone: (757) 269 7325 # # MS 16B, Room 16-125 fax: (757) 269 6273 # # Jefferson Laboratory pager: (757) 680 2036 # # 12000 Jefferson Avenue # # Newport News, VA 23606 USA # ######################################################### Dear Colleagues, Update for 970622: 00.00 - 11.30: 2.445 GeV, theta_pq = -16deg 11.30 - 16.00: recover from "brownout" 16.00 - 17.00: waiting for access 17.00 - 24.00: survey; move HRSh to theta_pq = -8deg The first half of the day went reasonably well with a good percentage of uptime. A brownout at 11.30 took the dipole power supplies as usual, and this time also took (permanently) the broadcast capability of the Q1 power supplies. We & Accelerator & Plant Services are desperately trying to locate the source of these brownouts, but no luck so far. We decided at 16.00 to cut our 2.445 GeV, theta_pq = -16deg point short at about 125 counts and move to theta_pq = -8deg. Survey and angle change rounded out the day. Kevin ######################################################### # K.G. Fissum phone: (757) 269 7325 # # MS 16B, Room 16-125 fax: (757) 269 6273 # # Jefferson Laboratory pager: (757) 680 2036 # # 12000 Jefferson Avenue # # Newport News, VA 23606 USA # ######################################################### Dear Colleagues, Update for 970623: 00.00 - 01.30: Accelerator tuning 01.30 - 04.30: Fix dead HV supply in HRSe 04.30 - 08.30: no useable beam 08.30 - 13.30: "brownout", survey theta_pq = -8deg 13.30 - 14.00: no useable beam 14.00 - 15.00: HRSh dump and recover 15.00 - 15.30: current calibration 15.30 - 00.30: 2.445 GeV, theta_pq = -8deg 00.30 - 01.30: move HRSh to theta_pq = +8deg 01.30 - 02.00: current calibration 01.30 - 08.30: 2.445 GeV, theta_pq = +8deg 08.30 - (?) : survey theta_pq = +8deg A long report to summarise my last day or so as Run Coordinator. The day started slow, and we decided to use the downtime to survey the spectrometer. "Brownouts" (if that is what they are) continue to play a role, and many continue to search for them. By 15.30 we were back on the air and current calibrated. The swing shift completed the theta_pq = -8deg point. HRSh was moved to theta_pq = +8deg just after midnight. The owl shift completed theta_pq = +8deg. As I write this, a survey is being performed. Progress! Kevin ######################################################### # K.G. Fissum phone: (757) 269 7325 # # MS 16B, Room 16-125 fax: (757) 269 6273 # # Jefferson Laboratory pager: (757) 680 2036 # # 12000 Jefferson Avenue # # Newport News, VA 23606 USA # ######################################################### The day shift started with the survey of H-arm at theta_pq=+8 degree. At around 1:30 pm, we moved the spectrometer to theta_pq=+16 degree, and surveyed again. Two people from CEBAF survey group were there for help. The survey finished shortly before 4pm. The hall was closed at about 6pm due to some other activities such as checking data acquisation system, magnets etc. MCC started to deliver CW beam of about 70 microA at around 7pm, and till 8am this morning we had accumulated about 10.5 hours data. According to the data taken, we need another 20 hours to get total 900 counts in p1/2 state with q,omega match (Larry is going to check the uncertainties if we change the total counts from 1700 initially wanted to 900). The "Brownouts" is still hunting us. We lost the magnets again yesterday at around 9am. All the controls are under UPS (uninterrupted power supply) system, but not the power itself. James Proffitt has checked all the UPS and found those UPS we were using doesn't have capacity, which might be part of the reason we can't survive the brownouts. The owl shift went smoothly. They spent the most time taking production data, did the BCM calibration at 2:45am. Some problem with DAQ but fixed in 10 minutes. Shortly before 8am, the CHL crashed, which shut down the whole accelerator. At the 8am MCC meeting, we were told that somebody untrained went into the compressor room without escort, and turned off the cooling water pumps!!! The estimate right now is it may take 4-6 hours to recover, which means that we may not see the beam during the day shift. The plan for next 48 hours is, when the beam come back, we will continue the data taking at +16 degrees. Then according to the situation, we will do the white spectra at either +16 or +20 degrees. Meme On June 25, the CHL crashed in the morning and didn't recover till about 8pm. Hall A started to receive CW beam at 10pm. But the beam was not stable, till 8am June 26, we only had about 4 hours data taking. The owl shift also saw some 60 Hz beam motion, although the effect on target position was small. At 9:00am June 26, MCC started to do the system check, which initially planned for about 1 hour. However they lost the network hub control at ~9:45am. They only manage to restart it at around 11am, by that time, Hall B was requiring the access which had been delayed. When the beam first came back, Hall B took their access. MCC didn't manage to deliver the CW beam immediately afterwards. We started to see stable CW beam at 3:15pm. By that time, Hall C wanted to do pulsed beam to check beam spot at first, BCM calibration next, followed by some calibration with different target. Since we can't use the beam during their BCM calibration, Alan Nathen had use the beam for his detector check. And we did our CM calibration right after their BCM calibration. Also since their changing target interrupted the beam, we took several short runs during that period. At 6pm, Hall C lost their HMS control during their calibration and required access. Shortly after that thunderstorms took MCC's power down. Beam came back about half an hour later. Later in the evening, Hall C did their beam energy calibration with pulsed beam from 8-10:30pm. Overall till 8:30am this morning, we got about 7 hours data, which is a little more than the goal we set for this angle. At 8:30am today, MCC is tuning the Hall B line trying to establish the 2 passes beam. It's estimated for 2.5 hours. We took the chance to move the H-arm and survey. CEBAF survey group provided 2 people and we waitted about half an hour for the RadCon survey to get the access. H-arm is at 72.5 degree (theta_pq=20 degree) now, and the survey is completed at about 11:30am. MCC was tunning Hall B line till 11:30am and was performing system check afterwardcs. We asked for beam permit at around 12:30. As to this point, 14:50, we are still waitting for the beam. Last update: MCC is tunning Hall C with pulsed beam. Hopefully we are the next. Meme At 4:00 pm yesterday, Hall A started to receive CW beam. It's later than we initially anticipated because to some reason, MCC was still tunning Hall B line after the time we agreed to stop. MCC didn't manage to deliver CW beam of 2passes to Hall B so was asking to switch to 5 passes to Hall B at later time. We started our program with production run at theta_pq=+20 degree for two hours so we had some estimates of the rate. The result: about 100 counts in p1/2 per hour. Larry did some quick calculations and now we are going to accumulate 1600 cts in p1/2 and 200-400 cts at theta_pq=-20 degrees. At 6:00pm, MCC started to switch the Hall B line for 5 passes. We started to set the H-arm magnets for the white spectra measurement. We got the beam back at around 8:45pm. At around 11:00 pm, cooling water stopped which triggered the ESR crash, which further tripped all our magnets. All three halls had been affected. By 1:15am this morning, the He level came back and we managed to reset all the magnets. White spectra continued till 6:30 am when we switched to normal production run. Bogdan also got some pion- in E-arm, while we were changing H-arm magnets for the white spectra. By 4:00pm today, we have accumulated about 1.1 Million coda events in total, which corresponding to 660 cts in P1/2. However since around noon time, there was some big beam motion at target (amplitude >1mm) observed. MCC was suspecting one of the three Moller quads in the hall was caussing trouble because they don't see the response from that quads. They were calling their experts in. At 5pm, MCC required access to the hall to check the Moller quads and find one of them was switched off. We have quickly checked those runs taken during the bad beam position, the energy resolution is slightly worse than the one without obvious beam motion. The possible runs might be affected: Runs 1967-1793. The estimate now is we need about 2.7 M total coda events at this angle setting. If the beam availability is good, we may be able to move the H-arm to theta_pq=-20 degree tomorrow morning. Meme It had been smooth data taking sinc last update. Till 8am this morning, we have had more than 2.7 million events for theta_pq=+20 degree. MCC was going to do their system check at 9am, so we decided to move H-arm to theta_pq=-20 degree at 9am. By 10:15am, we finished the access and returned to beam permit. MCC hasn't finished their check yet so we are still wait for the beam. If the beam situation keeps going on like the past two days, we may have a chance to see the data at theta_pq=+30 degree!! :) Just shortly before the access, the target computer frozen again. So we decided to postpone the reset of the computer and check what was going on in the hall. The outcome: the computer MacA in the hall WAS frozen. This means that the problem we had with the target is NOT due to the network. The computer in the counting house just "sees" whatever is happening to the computer in the hall. Meme As most of you already know, we have finished our theta_pq=-20 degree point. By 8:30 am we had taken more than 4 million coda events, which corresponds to 400 counts in p1/2. We had an access at 8:30am to survey the H-arm and then moved the spectrometer to 53.3 degree for FPP's use. There was a small celebration in the counting house around 1pm. Arun had brought with him the champagne and the cake with E89-003 on it. Of course, the person who made the cake was wondering what is "E89-003". :) Kees has suggested that we should start to check our data systematically and come up with a list in few weeks time for more beam request. There is a suggested meeting tomorrow morning around 10:30am, interested people should attend. Check with Meme. Meme