February 2016

STAR Newsletter

February 2016 edition

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BES Results & Activities
(Kathryn Meehan - Student, UC Davis)

Dear STAR Collaborators:

The past month or so has been very productive for Beam Energy Scan (BES) activities. In December, the Event Plane Detector (EPD) prototype was installed on the East side of STAR and is currently taking data. The EPD goals for the 2016 Run include testing the timing/triggering capabilities of the EPD, testing the overall integration, and testing the SiPM performance. For the near future, the EPD team is preparing for the March internal review of the EPD at BNL. To learn more about the EPD, please see You do not have access to view this node.

On Monday, January 25th, right before the start of the STAR Collaboration Meeting, there was an inner TPC (iTPC) director's review; those slides can be found here. Fortunately, the review was largely positive. One immediate recommendation was a request for a description of the physics impact of operating in Run 19 with a shorter run or previous generation of electronics mounted on the new iTPC sectors. One possible mitigation is to run with only half the channels of the inner sectors for Run 19. To learn more about the iTPC efforts see You do not have access to view this node.
Figure 1. EPD Prototype


The collaboration meeting took up the rest of the week with a morning plenary session devoted to BES physics. We had the pleasure of hearing invited speaker Marlene Narghang, a visiting postdoc from Duke University, give You do not have access to view this node. Daniel Cebra gave a complementary experimental overview of BES physics. He noted that the electron-cooling will be commissioned in 2019, so the current plan is to start with 14.5 GeV and 19.6 GeV energies in Run 19 without e-cooling while CAD is optimizing the system. Then data at 7.7 GeV, 9.1 GeV, and 11.5 GeV will be taken the following year with electron-cooled beams, since the e-cooling affects the lowest energies the most. The current proposal for BES-II is two 22 weeks of physics running in 2019 and 2020. He also noted that for the Fixed Target Program (FXT) the current STAR detector and software framework works well for injection energy and lower, that there are preliminary results consistent with published data, and that the statistics are DAQ limited. For more information see You do not have access to view this node. After the coffee break, the detector upgrade talks were given. Geary Eppley updated us on You do not have access to view this node. The letter of interest has been expanded to a full proposal that is ready for a STAR internal review which will probably take place within the next month. The following day Bingchu Huang gave a nice You do not have access to view this node. A PRL draft of a BES freezeout paper (Lokesh Kumar) is expected to be ready by March. You do not have access to view this node (Xianglei Zhu) is also making good progress. The Coulomb Paper (Brooke Haag) is currently in GPC and a GPC has been requested for the RCP paper (Stephen Horvat, Daniel Brandenburg; see the RCP figure below). Two independent analyses on light nuclei in BES agree (Rihan Haque and Ning Yu) and this result is being finalized. More physics statuses can be found in You do not have access to view this node. After the above analyses are published, a BES-I overview paper will be prepared.


Figure 2. RCP of inclusive hadrons in BES

Additionally, I would like to give a shout-out and special thank you to the production team as this February there was an official production of the 2015 Au + Au and Al + Au fixed-target test runs. Pending QA and embedding, a fixed-target analysis team involving multiple institutions and countries has assembled to publish a paper reproducing the AGS results. Preliminary results have looked strong, so expect final results to be presented soon.

Overall, plenty of work remains to be done to optimize the BES-II program. There has been a lot of progress in the past month and the outlook is good for an exciting physics program.

Kathryn Meehan


Collaboration Meeting Recap
(Zhangbu Xu - Spokesperson)

Dear STAR Collaborators:

We had a very productive collaboration meeting January 25th-30th, 2016 at BNL. The program committee chaired by Ernst Sichtermann did an excellent job in providing the collaboration with an exciting program. In this collaboration meeting, we held a townhall-style meeting, discussing STAR future scientific program and recommendations from the APS site visit. The STAR Council also invited BNL Associate Lab Director Berndt Mueller to present BNL’s RHIC future plan. Those activities were very informative and the feedback was very positive. There were also very helpful suggestions on similar events in future meetings. During the first day of the collaboration meeting, BNL (with representatives from DOE) held a director’s review on the STAR iTPC project. The committee addressed positively the three charges to the iTPC review on schedule, cost and technical capabilities. Subsequently, DOE approved the project in February 18, 2016 (for details, see Flemming Videbaek's contribution section). 

The summary of my Spokesperson’s presentation to council reflects a view of the state of the collaboration: With all the upgrades from 2008 to BES-II, which amounts to more than 50M$, STAR has become a very capable multiple-purpose detector in carrying out many of the scientific programs recommended by the NSAC in 2015: the upgraded RHIC facility provides unique capabilities that must be utilized to explore the properties and phases of quark and gluon matter in the high temperatures of the early universe and to explore the spin structure of the proton.

Two new universities applied for STAR membership without council seat: Council voted to accept both universities to STAR on February 12, 2016.
Congratulations and welcome back to STAR in your new roles, Jim and Evan! 

As part of the implementation suggested by the site visit from the APS committee on the Status of Women in Physics, the juniors invited Dr. Dan Magestro (business consultant, a former STAR collaborator) and Prof. Rosi Reed (assistant professor at Lehigh, a current STAR collaborator) to share their experience and advice on how to go to the next level in industry and academics. Congratulation goes to Alex Jentsch (UTexas) for being elected as one of the three junior representatives to the STAR council. I would like to take this opportunity to thank the out-going junior rep Joey Butterworth (Rice) for his support and effort in organizing many activities for juniors.

Sincerely,

Zhangbu Xu


Papers & Publications
(Frank Geurts - Physics Analysis Coordinator)

With the collaboration meeting early in this year, it was a good moment to take a look back at STAR’s publications of the past year. After the 2010 anti-4Helium paper in Nature, last year marked a 2nd STAR paper published by Nature. As you can see in the plot below (You do not have access to view this node), STAR’s output in 2015 has been above average and on par with that of the year before. While the number of Physical Review Letters dropped a little when compared to the record eight in 2014, we have seen a new record in the five papers to Physics Letters B that hit the press in 2015. All in all, the total number of letters (PRL+PLB) did not change at all between 2014 and 2015. The number of contributions to Physical Review C, which includes Rapid Communications, remained similar to what we published in 2014. The prospects for this year look already promising with two published and two accepted papers in less than two months and equally distributed between PRLs and PRCs.



A look at the Inspire.net citation summary shows that out of 184 published STAR papers (as per late Jan. 2016) nine papers are recognized as “renowned papers”, in other words have more than 500 citations. While there are other metrics available (think of Google Scholar), we have in the past many years used Inspire to provide a fairly reliable track record of STAR’s impact. What is interesting is to look which papers are possibly moving into the ranks of this illustrious 500+ category. Taking into account the trend of some of our top “famous” papers (250-500 citations), we can see two papers possibly knocking on the “renowned” door this year: our letter on the high-pT non-photonic electron suppression, PRL 98 (2007) 192301, and the comprehensive report on identified particles in p+p, d+Au, and Au+Au, PRC 79 (2009) 034909. At 479 and 469 citations, respectively, and consistently more than 30 citations per year in the past three years, you can start placing your bets.

To sustain such an impressive output, it is important that we keep a healthy input of paper proposals and drafts. Without going to much into the details (you should check out the paper report presentation at the collaboration meeting), we continue to see about twenty GPCs actively prepare new papers for review by the collaboration, and ultimately for submission to various journals. This effectively means that on the order of a hundred STAR members through their involvement in such committees are directly involved in the next round of publications. Going even further into the “prenatal” state of a paper draft, the physics working groups work together with PAs and so far have proposed more than thirteen papers to the convener’s panel with the intention to form GPCs in the near future.

Thanks to the relentless efforts of the people that designed, built, and operated the detectors, and thanks to similarly relentless efforts from all who help make all the STAR data available in the offline world, we can congratulate all in STAR for such a very healthy physics output. Let’s look forward to even more exciting physics and hope for many more of such productive years to come!


Operations Activities
(Bill Christie - Operations Leader)

Greetings to all from Long Island.

In the past month STAR has gone from first two person shifts for cosmic ray running, through the detector setup with collisions, to our present state of taking production physics data. A timeline for how this went is:

January 12th – We started two person shifts. On this date we also started the flow of flammable gases into STAR, and starting taking cosmic ray events without the TPC for use in the silicon sub systems alignment. We also use this early running for commissioning and bringing back online the entire detector.

January 16th – Whereas the TPC electronics had been included in the earlier Cosmic Ray data taking, on this date we started running the TPC with the HV on.

January 19th – The RHIC cooldown from liquid Nitrogen to liquid Helium temperature begins. STAR Magnet turned on for continuing cosmic ray running.

January 25th – Collider commissioning with beams begins.

February 3rd – First overnight collisions for Experiment setup. We find that the STAR global timing is the same as Run 15, and start on trigger detector gains and TAC offsets.

February 7th – “Physics Running” is declared. We elevated a few Triggers to Physics IDs, and then commenced with working our way through all of the planned triggers, checking and tuning them as needed, and elevating them to physics IDs.

As I write this, February 18th, we’ve got the entire physics program up and running, overseen by our first Period Coordinator of the Run, David Tlusty [Rice University]. There has been continuing effort with the Trigger and electronics groups, with input and analysis help from other STAR collaborators, to work on plans to improve the precision of the Level 0 timing cut for the HFT physics program. At present it looks like the precision of this vertex cut will improve, following a different path than originally planned. An estimate is that this improvement will come online early next week.

The collider tuning is also continuing at this point. There is an issue with the RHIC beams “debunching” (getting out of the desired RF buckets) which the collider is still working to understand. Once this issue gets resolved we expect to get to the long store lengths that we need to reach our ambitious physics data set goals for the 200 GeV AuAu run.



iTPC Project Update
(Flemming Videbaek - Upgrades Leader)


The iTPC project has made great progress thanks to the effort of a large number of people. The status of the project was presented at the collaboration meeting in January. It had just had a successful director's review on January 25th. Following this, BNL management had discussions with the office of Nuclear Physics at the budget briefing in early February, and on February 18th between DOE NP , BNL NP, and STAR to clarify the status. Subsequently Berndt Mueller sent a letter to STAR with the following content:

Dear Zhangbu:

Today we received official permission from the Office of Nuclear Physics to “cautiously” proceed with the STAR iTPC upgrade project. Flemming Videbaek will serve as the Project Manager. This decision, which is in recognition of the critical importance of the iTPC upgrade for the success of the RHIC Beam Energy Scan II, will allow us to initiate long lead time contracts and procurements. We have been asked to submit a detailed Project Management Plan no later than March 31, 2016, which will define the organization, schedule, and milestones for the project and address various other aspects critical to the success and timely completing of the upgrade. We have also been told to expect an early performance review of the project in mid-summer 2016.

We are very much pleased with this decision by DOE, while we recognize that the project faces many challenges that will need the full attention of the project team and the STAR collaboration.

Best regards
Berndt & Jamie

On this basis, STAR and the iTPC project will develop the management plan, and at the same time proceed with the urgent need to finalize the design of the pad plane, and the design of the strong backs so we can proceed in accordance with the overall plan to setup and start the procurements of these time critical items.

The strong support in the collaboration from the technical team, the simulation team, and the physics proponents has been critical in getting to this point. The path forward is challenging and needs continuous strong efforts.


Previous Edition: December 2015