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STAR Newsletter #88January 2002 |
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| Star Home Page |
Editor: Howard Matis
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STAR Newsletter #88January 2002 |
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| Star Home Page |
Editor: Howard Matis
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John is on travel so there will be no column this month.
No contribution this month.
FTPC (from Volker Eckardt)
No contribution this month.
Slow Controls (from Mike Cherney)
The magnet monitor program (monitoring data from the RHIC control system) has been modified to better identify magnet trips. The SMD has been included in the slow controls database. The EMC and SMD status can be monitored from the alarm handler. Work continues on a prototype standalone system requiring only a PC (no SUN station) for slow controls operation.
EMC (from Alexandre Suaide)
No contribution this month.
TPC (from Blair Stringfellow)
No contribution this month.
Level 3 Trigger (from the commissioning contingent)
No contribution this month.
Endcap EMC (from Will Jacobs)
No contribution this month.
RICH
No contribution this month.
TOFp - (Bill Llope and F. Geurts )
No contribution this month.
The emphasis of the RHIC/STAR accelerator/detector during this period has been to commission RHIC for p-p running at sqrt(sNN)=200 GeV. On the RHIC books (and in reality!) the time usage was:
- 129 hours machine development
- 15 hours experimental access
- 7 hours scheduled maintenance
- 37 hours miscellaneous
The up time of RHIC has been much better during the p-p commissioning than for Au-Au commissioning or running.
RHIC
- Development work has continued on ramping of the blue and yellow beams in RHIC from 24GeV to 100GeV. Both beam quality and intensity are being worked on; and 55 bunch stores in both rings are now normal. Progress has been sometimes sporadic, but it is monotonic positive. Hitting the luminosity target for year 2001 running by early January is not out of the question.
- Work on the polarization of the proton beams in the blue and yellow rings has been progressing.
- The invaluable diagnostic tool represented by the RHIC CNI polarimeters has been operating quite well.
- There is ~100% transmission of the proton beam polarization from the AGS to the RHIC rings at the RHIC injection energy of 24GeV. However, the polarization of the proton beams extracted from the AGS is now quite a bit lower than the projected value of 50% for the AGS proton beam polarization at 24GeV.Usually the transferred beam polarization is 20-23% with maximum values of around 33-35%. The AGS is being worked on and it is hoped that extracted beam polarizations of at least 45% can be obtained by the end of the p-p running period on 24 January.
- Proton beam polarization is being transferred in the RHIC rings during the ramping from 24GeV to 100GeV; and this polarization can be stored for long periods - at least 8 hours - at 100GeV. The confirmation of this statement by the RHIC CNI polarimeters was the most exciting development during the 10-17 December period and lead to a BNL press release. The quantitative fleshing out of this statement awaits more systematic data; and a great deal of development work is needed to maximize the polarizations of the stored proton beams. The polarization group is sending out E-mail on a daily or near daily basis; and getting these E-mail is a good way to follow the progress on this very important front.
- The production of 55 bunch stores in the rings with each bunch tagged with regard to its polarization is now routine.
- A lot of RHIC machine development work is yet to come.
- Conversion at store to 200MHz RF frequency. This will decrease the bunch length, and therefore the length of the collision diamond. This is being worked on now.
- At 100 GeV commissioning of the down ramp of one of the two snakes. This is necessary for the production of longitudinally polarized beams at the RHIC interaction regions. This commissioning is being held off until at least the beginning of January.
- Down ramping the polarized beam from 100GeV to 24GeV and measuring the polarization at 24GeV with the RHIC polarimeters. Given the state of RHIC's proton polarimetry this is necessary to determine the beam polarization at 100 GeV and to calibrate the CNI polarimeters. This operation will also be held off until at least the beginning of January.
- Ramping of polarized protons to 250GeV. This will be done only at the end of p-p running ( 24 January ).
STAR
STAR was quite active during this machine commissioning period. Under Blair's able stewardship the TPC was brought back into operation. A 5 hour access on Thursday, 13 December, was used by many subsystem groups: RICH ( Jamie ), BEMC ( Alex, Marsha, Steve ), BBC ( Les, Greg, Brend, Akio ), TRIG ( Hank, Bill, Tonko, Jeff )and SVT ( Dave ) to develop and improve their systems. With regard to the BEMC 21.5 modules now have their towers and SMD's in operation - 860 PM's are working and 500 are in the trigger. The L3 group has produced a vertex finder to work under the conditions of p-p collisions; that is, sparse track densities.
The two main operations of STAR during this period of RHIC p-p commissioning were concerned with the production of usable trigger configurations for STAR, coupling in the various STAR subsystems and with commissioning the beam-beam counter( BBC ) system, and thereby producing an adequate min-bias trigger for STAR p-p running. The first of these tasks was performed mainly on Saturday, 15 December, when p-p collisions in RHIC ( and STAR! ) were provided through the intervention of the RHIC accelerator chief, Tom Roser. As of 6 PM Saturday, 15 December, the CTB, the blue beam, the yellow beam, BBC#1, and the Forward Pion Spectrometer gave bits which were usable in the trigger; and there was a trigger configuration - bbcTrigger. Kudos to Hank, Les, Jeff, and Bill! During this period the BBC group - Les, Akio, Greg, and Brend - worked around the clock on the hardware and software for this important detector array. They have evolved a system which defines both a min-bias trigger for about 40% of the total p-p cross section and a calibrated interaction length within the STAR TPC. Great job!
I believe that all the shift crews who worked during this week should pat themselves on the back: "They also serve who sit and wait." The STAR counting house was usually filled with motivated STAR collaborators working on STAR-related physics problems even when STAR shift-related tasks were at a minimum. We have placed ourselves in a great position to take about a month of exciting p-p data, hopefully with a lot of spin!
The pp run officially started at 00:00 21 December. Through 12:00 December 30, STAR has recorded 3M min bias events. RHIC delivered beam to STAR during 39% of that period and STAR recorded physics data during 50% of the available beam time. The peak luminosity that has been achieved is 0.6 x 10-^30 and the maximum polarization seen in RHIC at 100 GeV is < 20%. The higher luminosities were just achieved in the past 24 hours and useful polarization has not yet been measured at these luminosities.RHIC delivered beam to STAR (measured from the time it is steered until the time we are asked to power down) for 39% of the available hours. About 2% of the available hours were access for the experiments.
STAR used 16 hours of beam time for commissioning the new detectors: FPD and EMC. For the remaining 73 hours, we took data 50% of the time.
The 24 hour down time was: magnet and chiller trips, 7h, magnet power supply regulation problem, 13h, and daq and l3 reboots, 4h. We are about 75% efficient at taking data outside of major down time.
Detector operation:
- TPC and FTPC: normal operations with only an occasional trip induced by RHIC. TPC sector 14-3 is masked out for the pp run to date.
- RICH: normal operation with occasional (daily) trip
- TOFp: normal operation
- SVT: has not been in the pp run and is on holiday until January 2. It is reported to be ready to run.
- Magnet: is currently operating very reliably with no trip since December 24. Runs 2360002 - 2363078 have 0.4 % higher field.
- DAQ: in general operates reliably for long stretches of time with a few occasional glitches requiring reboots. The daq rate for min bias as measured over very long runs is 38 Hz.
- L3: has learned to accommodate pp events and is now running more or less robustly. It crashes frequently at `end of run' but rebooting is now a 15 second operation.
- Trigger: runs reliably. The spin bits are timed in and are being written correctly in the trigger word. The 48-bit bunch number appears in the output record but is not being initialized with the revolution signal at the beginning of the run. Therefore the bunch number obtained by dividing the 48-bit number by 120 has a random orientation in each run. The 7-bit bunch id is not currently in the event record. The revolution counter is not timed in. The scaler system which is needed to provide scaler information by bunch crossing is being included in the runs but it has not been determined yet whether the scaler board is producing reliable information. The inputs to the scaler board have not been timed in.
- EMC: The EMC trigger is still being commissioned.
- BBC: operating reliably as the minbias trigger. About 1% of the events are bad events due to timing of the hand shake between BBC and DAQ and to missed trigger tokens.
- FPD: operating reliably as a detector and trigger. The scaler system at the FPD can provide spin-sorted scalers for the yellow ring. The scalers are almost timed in and should be available soon. This will allow the FPD to begin the single spin asymmetry measurement of forward pi0s.
- Offline: We are not receiving any reports on data quality. The only QA information we have comes from the L3 online histograms which are invaluable. Also the FPD and EMC groups are here looking at their data.
- Polarized RHIC: Beam lifetimes are long and the half-life is 6-8 hours or sometimes more. The machine operates reliably with low down time from component failure. It is operational ~85% of the time. Quench lock interlocks are rare at this beam energy. Luminosity needs to increase by a factor of 4 to meet this year's goal of 10^30 over a store. The apparent, uncalibrated polarization needs to increase by a factor of 2 in RHIC. The RHIC polarimeters need to be calibrated at 100 GeV by down-ramping to 25 GeV and re-measuring polarization.
There is a physics request for a CTB trigger in the pp run. This is available in the trigger but the trigger board is waiting for physics groups to analyze the offline data and propose thresholds and rates.
STAR will likely achieve the goal of 20 M minbias events and can make a single spin asymmetry measurement with the FPD at the current luminosity if polarization improves. Increased luminosity will allow the FPD to move further from the beam pipe and make a better measurement at higher pT.
No contribution this month.This section contains summaries of the status of the physics working groups. These articles are in a protected area for STAR collaboration members only. This link uses the standard STAR account and password for physics results. If you do not have this information, please contact your council representative.
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Report from the STAR Council (Jay Marx)
The STAR Council met at Brookhaven on December 7, 2001. The following actions were taken by the Council:
- Changes to STAR Bylaws for the selection of Spokesperson and Council Chair were approved. These changes are reflected in the Bylaws that are now accessible through the STAR web site.
- Jay Marx (LBNL) was elected Chair of the STAR Council for a term of 2 years.
- The process leading to an election of the STAR Spokesperson was initiated. A nominating committee (Jay Marx (LBNL), Mort Kaplan (Carnegie Mellon) and Tom Cormier (Wayne State)) was set up by the Council Chair according to new Bylaws to solicit nominations and to prepare and oversee the ballot. A call for nominations from the Collaboration was issued by the Council Chair with a 12/28/01 closing date.
In mid-January 2002 the Nominating Committee will inform the Council and the Collaboration of the candidates who will appear on the ballot and candidate's statements will be distributed. The election will occur at the February 8, 2002 meeting of the Council.- At the Council meeting, the STAR Spokesman (John Harris, Yale) introduced the Council to changes in the STAR organization that he considered necessary in the light of the evolution of the experiment to one where physics analysis was intense. These included moving the Physics Analysis Coordinator to the Spokesperson's Office and the appointment of two new Deputy Spokespersons. The Spokesman asked that the Council approve Rene Bellweid (Wayne State) and Thomas Ullrich (Brookhaven) as the new Deputy Spokespersons.
The Council approved the appointments of Rene Bellwied and Thomas Ullrich as Deputy Spokespersons.
The Spokesman also announced that Mike Lisa (Ohio State) is the new Physics Analysis Coordinator and that Tom Ludlam (BNL) has agreed take over as Head of New Detectors and AEE from Jay Marx on January 1, 2002.
Assistant Professor - University of Kansas
The Department of Physics and Astronomy at the University of Kansas, Lawrence, seeks to fill a tenure-track faculty position in experimental nuclear physics. The appointment will be made at the rank of Assistant Professor. The position is contingent on final budgetary approval. Further particulars regarding this position are listed at this web site. Initial review of applications will begin on January 21, 2002 and will continue until the position is filled.
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