STAR Interactions

March-April 2003

 

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Contents

  1. Spokesman's Column
  2. STAR Operations
  3. Persona Grata
  4. STAR Upgrades, R&D etc.
  5. Period Coordinator's Report
  6. Council Affairs
  7. People: Service Jobs and more
  8. Announcements, Papers and Notes
  9. Ten Years Ago in STAR
  10. Employment Opportunities

Spokesman's Column (Tim Hallman)

It was another very productive month for STAR, both in the counting house, and "offline".

With regard to the ongoing run, there was significant progress in enhancing our statistics for the min bias and triggered high pt data samples. In addition, a dedicated sample of approximately 2.4 M events were taken using a trigger based on a particle being present in the TOFr prototype. These data provide an exciting glimpse into the enhanced capability STAR will have with the proposed barrel MRPC TOF upgrade. Statistically robust samples of UPC triggers have also been taken, promising to greatly extend STAR's reach in studying coherent particle production. Test data are being taken now for a prototype J/Psi trigger, which we hope to have running at Level II for the upcoming proton run. In the final days of the d+Au run, we will concentrate on taking FPD triggered data to attempt to get a measurement of the gluon distribution in the Au nucleus.

A very positive aspect of this run has been the aggressive approach we have taken to production of the data. After a brief pause to take care of some "housekeeping issues" (e.g. disk space), production has begun again, and we are well on the way to having 30-40% of the d+Au data already analyzed by the end of the d+Au part of the run. Embedding is also getting underway. This hard work by the software and computing team has really paid off, affording early hints of very exciting results, which make us want to analyze the rest of the data just as quickly. The ITTF effort is progressing steadily with evaluations of performance underway.

Last week, the Strange Quark Matter conference was hosted by Duke, BNL, and MIT in Atlantic Beach North Carolina. It will come as no surprise to those who attended when I say that STAR really stole the show in terms of the vast amount of exciting new results presented. All of our speakers did a great job, and are to be congratulated. Thanks are due to Rene Bellwied, Helen Caines, Zhangbu Xu, Raimond Snellings, and Jamie Dunlop for helping our speakers to get ready and to all those who worked hard to insure a successful meeting for STAR.

As successful as the d+Au run has been, the polarized proton run promises even more advances. This past week, discussions with the DOE by BNL Management resulted in a plan to insure the run would continue for the full 29 weeks. Also, a decision was taken to switch to polarized protons on Monday, March 24th. We look forward to enhancing our previous measurement of the transverse asymmetry for forward pi zeros, and to a possible first measurement of the sign of the spin dependent gluon distribution of the proton (delta G(x)),-- both measurements of world-wide interest. All in all, this promises to be a very exciting spring and summer for STAR and for RHIC, thanks to your hard work. Keep up the great effort!

STAR Operations (Bill Christie)

Greetings from Long Island. We've received quite a bit of snow here on Long Island through February and early March. I believe our total snowfall for the season is now over four feet (>122 cm). Along with the snow have been many weeks of sub freezing temperatures. I for one am eager to start seeing signs of the coming Spring.

The data collection has gone fairly well for the last month. When I composed the February Newsletter contribution we were just getting started on using a Run Configuration, called dAuCombined, which allows us to collect our minimum bias and High Pt data sets in parallel. This run configuration contains our four minimum bias Trigger Identifiers as well as two BEMC high tower thresholds. The prescales have been adjusted so that we typically take about 40 Hz of min-bias, about one Hz of our low (~2.4 GeV) BEMC tower threshold (High Pt-1), and about 1 Hz of the high (~4.4 GeV) BEMC tower threshold (High Pt-2) events, while maintaining a "live time" of about 50%.

As of today (Friday March 7th) we've collected about: 10.9 million events of min-bias with Full Forward magnetic field 19.2 million events of min-bias with Full Reverse magnetic field for a total of just over 30 Mevts of min-bias. This corresponds to about 42% of our goal of 70 Mevts of min-bias.

We've collected a total of about 315 kevts of High Pt-2 events. By analyzing our scalers and prescales it has been determined that the cross section for satisfying our High Pt-2 trigger is about 0.24 mb. Working through the numbers one finds that this 315 kevts corresponds to about 1.31 inverse nb of integrated luminosity. As the fraction of live time that we choose to make available for our High Pt trigger is up to us (STAR), it has been decided that we'll report our progress in accumulating our High Pt data by doubling the integrated luminosity that we've collected onto tape (i.e. we've chosen to run with a 50% live time). Applying this factor of two, one finds that we've sampled 2.6 of the 25 inverse nb that we choose as our goal for this year's d-Au run. This corresponds to a bit over 10% of our goal.

In addition to continuing to accumulate our min-bias and high Pt data sets, we have a number of near term commissioning tasks that are being worked on. One of these near term tasks is setting up for, and taking a "TOF" data set. The goal of this data set is to enhance the yield of events that have tracks which hit the TOFr slat by something like a factor of fifty over the yield of these events that one gets in our typical min-bias events. We hope to get the trigger for this TOF data set tested very soon. The request is that we accumulate 2 Mevts with this trigger.

An additional commissioning task that is ongoing is the setup, and eventual data taking, of an Ultra Peripheral Collisions (UPC) trigger. From tests done already it appears that one can get an efficient (i.e. high yield of reconstructed rhos) UPC trigger by adding on the requirement that the deuteron involved in the UPC events breaks up (i.e. require a neutron in ZDC West). The near term plan is to study the effects of varying beam conditions (luminosities and backgrounds) on the UPC triggers, and then decide the best way to run them and how many events are required.

A continuing commissioning task is the setup and testing of the J/Psi trigger. As part of this effort there have been ongoing efforts to identify and mask out individual BEMC towers that have high or broad pedestal values. Other aspects of getting the full J/Psi trigger functionality online include getting all of the "raw" BEMC tower data passed to the trigger L2 CPUs, getting the J/Psi invariant mass code ported to the L2 CPUs, and commissioning the L2 event abort capability. Efforts continue serially on these three remaining aspects of the J/Psi trigger.

One more commissioning task that is getting looked at is getting a BEMC Jet patch (i.e. 1 x 1 in eta and phi) trigger online. There are some issues of the widths of the Jet Patch pedestal distributions, some portion of which seems to be associated with correlated pedestals between towers, that are being investigated.

Other continuing efforts arre the setup and debugging of the FPD electronics, the testing of the PMD, the testing of the SSD ladder, and the debugging and integration of the EEMC.

In the background, behind RHIC stores, efforts have been going on for a number of weeks now to commission the polarized proton source and the AGS for the upcoming polarized pp run. As of the writing of this contribution I haven't heard any reports of the polarization of the AGS beams at the RHIC extraction energy. I expect to begin hearing more about this as we go through the next few weeks.

Finally, it was very exciting to see the first results from the d-Au min-bias data set that were presented at the recent STAR collaboration meeting. From what I saw it looks like we have a good quality min-bias data set. I'm looking forward to see some of the reconstructed data from our high tower triggered events soon.

Bill Christie

Persona Grata

        This month's persona grata is Jay Marx,

     
Interviewed by Eugene Yamamoto
 

STAR Upgrades, R&D etc.

New Detectors in STAR

New Detectors in STAR

By Jim Thomas

 

STAR has several new detector sub-systems that are making progress towards becoming important elements of the full detector.  The list includes the Silicon Strip Detector (SSD), the Barrel Electromagnetic Calorimeter (BEMC), the Endcap Elecromagnetic Calorimeter (EEMC), the Forward Pion Detector (FPD), the Photon Multiplicity Detector (PMD), two flavors of Time Of Flight (TOFr and TOFp), and of course the SVT is an old friend that still deserves some attention as a “new” detector.

 

I have a strong interest in these detectors because I will be serving as the collaborations point of contact to the Department of Energy for these new detectors and I will be working along with the respective project managers on each project to ensure that the DOE gets timely updates on the sub-systems progress.  I’m looking forward to the job and I think it will be fun.  It will force me to learn a great deal more about these detectors than I already know.  Two systems that I recently spent time studying include the EEMC and the FPD. 

 

The EEMC, sometimes called the Endcap Calorimeter, is the natural complement to the STAR barrel calorimeter because it closes the gap in our coverage on the west end-cap of the magnet.  This, of course, is a critical rapidity interval which allows us to study jets and hard parton scattering events.  The kinematic coverage provided by the EEMC is crucial to STAR’s goals of measuring the polarization of quarks and gluons in a polarized proton, especially at low Bjorken x.  The detector is composed of 23 layers of Pb and Stainless Steel absorber interleaved with 24 layers of plastic scintillator.  The design includes a shower maximum detector and it has lots of segmentation which allows us to trigger on topologically distinct patches of the detector.  The EEMC group has recently completed installing the lower half of the detector structure and they have instrumented 4 of the 6 sectors in that half.  They have had a brief look at detector performance with the d-Au beam and they are looking forward to triggering on real physics events during the p-p run.  The best part of the EEMC is that it is being built and funded by IUCF and the NSF.  For more information see:  http://www.iucf.indiana.edu/U/STAR/eemc_proj/

 

The Forward Pion Detectors go to even more extreme rapidities and, in fact, they are installed as close as possible to the beam pipe at about 7.5 meters from the interaction vertex.  There are will eventually be 4 detectors on each end of STAR; each with a 24 layer Pb-scintillator stack and a shower max detector and a pre-shower detector.  Currently the west end is complete. The detectors are arranged in a top, bottom, left, right configuration which makes it ideal for measuring spin asymmetries in pi-0 production, among other things.  The East end only has 2 detectors (top and left) and this configuration was chosen to help with commissioning of the spin rotators by making sure that the transverse component of the polarization has been tuned to zero. The other 2 detectors on the East end will be added next year. The FPD is funded by the DOE but it is cleverly being built on a shoestring budget. The FPD group has already produced significant physics from last years proton run and they are looking forward to the analysis of this years data (both d-Au and p-p) with a significantly improved detector compared to last year. For more information see:http://www.star.bnl.gov/STAR/html/fpd_l/index.html

 

 

Period Coordinator Reports

The Period Coordinator Hypernews Archives are here

The most recent reports are:

15-22 Feb 2003

1-8 March 2003

9-14 March 2003

15-24 March 2003

Council Affairs

Contributed by Jay Marx

Summary of February 27, 2003 Meeting of the STAR Council

The STAR Council met on February 27, 2003 at Brookhaven during the Collaboration meeting. There were a number of important items of business including the election of a new Council Deputy Chair who will become the Council Chair in a year, consideration of whether to extend the charter of the Advisory Board, a vote on whether to submit STAR's proposal for a full barrel RPC-based time-of-flight system to Brookhaven management and DOE for funding, consideration of applications of three new institutions to join STAR, reports from Council committees which included proposed changes to the STAR publication policy, and the scheduling of the next two collaboration meetings. The meeting was chaired by Mort Kaplan, the outgoing Deputy Council Chair. The minutes from the meeting can be found on the STAR web-site under "Council".

Before summarizing the meeting Council I want to thank Mort Kaplan for his efforts as Deputy Chair of the Council and especially for his support, wisdom and excellent advice during the past year.

A brief summary of the actions taken by the Council follows:

1. Bill Christie (Brookhaven) was elected as the Council Deputy Chair. He will become Council Chair for 2 years beginning at the January 2004 Council meeting.

2. The Council voted to continue the charter of the Advisory Board indefinitely

3. The Council voted unanimously to proceed with the Proposal for TOF Barrel based on MRPC Technology.

4. Tim Hallman presented his Spokesman's Report to the Council.

5. Three groups have requested to join STAR, Cal Tech, NPI (Czech Rep.) & Zagreb Groups . The necessary 75% of Council members were not present, and so no formal vote to admit was possible at this meeting. However straw polls on all three applicant institutions indicated no opposing votes. A formal vote will be conducted by e-mail. [editorial note: This process has been finished and all groups are now STAR institutions].

6. The report from Council Service Committee-summarized the status of efforts to match-up available manpower with unmanned or undermanned tasks. There was wide agreement in the Council that this effort has been very p roductive and successful.

7. The report from Council Publication & Talks Policy Committee summarized several Publication Policy changes recommended to the Council by this committee. These changes involve formalizing the procedure of early preview by the PWG Convenors of proposed papers, making referee reports and replies to same available to the collaboration, policy on single- or few-author papers based on preliminary STAR results, and policy on erroneous publications. The Council voted to adopt the changes recommended by the Publication & Talks Policy Committee. (The text of the adopted policies can be found on the STAR website under organization)

8. The Junior Members representatives reported to the Council that there are currently about 100 juniors and there have been 15 PhDs so far based on STAR. A number of concerns of the Junior Members were discussed with the Council.

9. The scheduling of next two collaboration meetings was discussed. It was agreed that the next STAR Collaboration Meeting will take place during the week of August 11, 2003 at Michigan State. The next meeting after that will likely be held during the first week of January 2004 (just before QM 04). The location of that meeting remains undecided, but it will not be too far distant from the Oakland, CA location of QM 04. Alternatively, a STAR Analysis Meeting may be scheduled in proximity to QM 04 and immediately preceding it, in which case the Collaboration Meeting may be deferred until spring, 2004.

People

Announcements, Paper and Notes

Publications:

The following papers have been recently published:

  1. Disappearance of back-to-back high pT hadron correlations in central Au + Au collisions at sqrt(snn) = 200 GeV
    C. Adler et al. Phys. Rev. Lett. 90, 082302 (2003)
    Published: 28 February 2003

Ten Years Ago in STAR

  • Coffee was complimentary at Collaboration meetings; it now costs $100!

Employment Opportunities

Online Computing and Server administrator

For more details ask Jerome Lauret


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