June 2018

STAR Newsletter

June 2018 edition

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A note from the editor: as a collaboration-wide communication tool, this newsletter is set up to allow comments (subject to moderation against abuse), and all STAR Collaborators are welcome to do so! Please keep in mind that some content (including all comments) may be considered internal to the Collaboration and only accessible when logged into Drupal. Documentation is available here.

From the Spokespersons
(Helen Caines - Co-Spokesperson)

A belated Happy 4th of July to those of you living in America.

STAR had a very successful Run 18, far surpassing our goal of 1.5B events for the both Ru+Ru and Zr+Zr collisions for CME studies. Thanks go to C-AD for providing incredibly stable luminosity levels, long stores of 20+ hours, and daily switching between isobars to minimize systematic uncertainties. In addition, excellent data at 27 GeV and 3 GeV were collected. The EPD, the first sector of the iTPC, and an eTOF module, were commissioned and operated at, or beyond, specifications. The remaining iTPC and eTOF modules will be installed during a very busy summer shutdown in preparation for the much-anticipated BES-II.

As always, STAR had a strong presence at QM18 (see the contribution below), special congratulations go to Daniel Brandenberg for being awarded a flash talk due to his excellent poster. I also want to give a special thanks Zhenyu, Grigory, and the conveners for their dedication and hard work, especially at the pre-QM meeting in Warsaw, helping the speakers prepare and cross-check their data.

We have just received the 2018 PAC report in relation to our BUR and they agreed we should place highest priority on accomplishing the BES-II program, and commended STAR for developing and sharpening our forward physics program, which enriches the range of future opportunities for BNL.

We continue to be scientifically productive, since January STAR had published 6 new papers and submitted 6 others. From the Heavy-Ions side the topics of these papers range from investigating the beam energy dependence of jet quenching, rapidity-even dipolar flow and directed flow of strange hadrons, the hypertriton’s lifetime, low-pt dilepton pair production, global hyperon polarization at 200 GeV, the elliptic flow of the D0, correlations between flow harmonics,  and J/Ψ production in pp. The Cold QCG/Spin groups have reported on the transverse spin-dependent correlations of charge pion, the azimuthal transverse single-spin asymmetries of inclusive jets at 500 GeV, and the longitudinally double-spin asymmetries of di-jets at 200 GeV and forward π0s at 510 GeV.

The RHIC/AGS Users meeting was also very successful for STAR. Dr. Jan Jan Rusňák and Dr. Ting Lin were awarded the Best Thesis prize, while Amani Kraishan won the best poster. Merit awards went to Jim Drachenberg, Xiaofeng Luo, Takafumi Niida, and Isaac Upsal, while Sevil Salur was elected incoming Chair and Oleg Eyser, Frank Geurts, Sooraj Radhakrishnan, and David Tlusty were elected to the executive committee (see all their faces in the segment further down this Newsletter).

Finally, congratulations to Dr. Zhen Liu, Dr. Maowu Nie, and Dr. Shenghui Zhang who recently passed their Ph.D defenses, and happy 60th birthday Peter Jacobs!

I look forward to seeing you all in Lehigh at the collaboration meeting!

Helen



Daniel presenting his flash talk at the conference
[source: Quark Matter 2018]
Quark Matter Summary
(Daniel Brandenburg - Rice University)

Quark Matter 2018, the XXVIIth international conference on ultrarelativistic nucleus-nucleus collisions, was held at the Palazzo del Cinema on the beautiful island of Venezia Lido, Italy from May 13th to 19th. As always, STAR had a strong presence at this Quark Matter with 19 invited oral presentations, 1 poster flash talk, and 32 poster presentations. In addition, several of our very own STAR collaborators gave invited plenary presentations: Zhenyu Ye presented the STAR highlights talk, Li Yi presented an overview of small systems, Rosi Reed discussed measurements of fluctuations in nuclear collisions, Rongrong Ma presented an overview of quarkonia production, and Tetyana Galatyuk discussed future facilities for high-μB physics. Another unique aspect of this Quark Matter - it also featured a photo contest challenging us to submit photos related to the theme "Color deconfinement in Venice" with many incredible photos submitted.

Out of the nearly 400 posters, I had the honor of being one of 10 posters chosen for a 5 minute plenary "flash" talk. My poster presented ongoing work to measure the dimuon (μ+μ-) invariant mass spectra for the first time at STAR using the Muon Telescope Detector (MTD). Traditional PID techniques using dE/dx and Time-of-Flight are unable to distinguish high momentum muons from charged pions since the masses are so similar. In my poster I highlighted the use of deep neural networks (DNN) and other multivariate techniques for muon identification using the MTD information. I also presented methods I developed for verifying the features and relationships learned by the DNN so that its uncertainties and limitations can be fully understood. Finally, I presented the raw μ+μ- invariant mass spectra from Run 15 p+p collisions at √s = 200 GeV, comparing the result from traditional muon identification versus DNN-based muon identification. The DNN-based muon identification shows significant improvement in the significance and signal-to-background ratio of the ω, φ, and Ψ(2S) mesons making their measurement possible.





Compression gains on isobar data currently available from ROOT; STAR has historically used compression level 9.
Software & Computing Tackles Data Storage
(Jérôme Lauret - S&C Leader,
Gene Van Buren - S&C Co-Leader)

The STAR S&C Team is happy to mention we were granted a Small Business Innovation Research (SBIR) award in partnership with Accelogic LLC for a research proposal titled “Next-Generation Technology for the Extremely Efficient Storage, Distribution, and Processing of Nuclear Physics Data”. Accelogic was founded as a spin-off from state-of-the-art research performed at Bell Labs. Accelogic was strategically established with the main intention of applying core technologies, theories, ideas, and concepts and target the groundbreaking acceleration of any software through novel, easily-injectable techniques. Their first success stories were on accelerating workflows on High Performance Computing (HPC) (via Compressive Computing applied to floating point operation and data exchange). Leveraging their accumulated crucial know-how, they are now tackling the challenge of data storage.

The core of the proposal outcome would be to provide a state of the art compression algorithm that surpasses those currently available in the ROOT framework. In our (very) preliminary study, nearly a factor of x2 additional compression on top of the standard gzip methods was achieved, opening the realm for huge space saving (or more dataset made available online). A typical compression gain using gzip in ROOT is shown below for our MicroDST and picoDST formats respectively (the error bar represents the spread over a data sampling of our recent isobar datasets). It is clear that compression varies over our data format and for our picoDST they are at best a ~1.55 compression gain using maximal gzip level 9. In our initial study (using Au+Au 200 GeV), ROOT provided at best a compression factor of ~1.4, while using Accelogic’s methodology, we reached 2.37 or a net gain of ~1.7 on top of what ROOT is currently capable of.

Au+Au 200 GeV picoDST compression gains from initial studies.
It is important to stress that the method employed is “lossless” (no precision is lost in the process) by employing a “zero-information bearing bits” or “zibbits” method. Such method has been used in other fields - in particular, Accelogic was able, after some research efforts, to provide a compression factor of x12 with several of NASA’s data. Similarly, we hope to achieve factors beyond our initial quick study. We expect to have a better understanding of the gains by the end of the year (many datasets and data formats will be investigated).

Needless to say that during a kick-off meeting that was held in Washington D.C. at the end of June, many agency managers were extremely enthusiastic with the prospect of this research. All communities, from the ones at the LHC to the ones from future Nuclear Physics experiments, envision tomorrow's datasets to be an order of magnitude larger than those acquired today. The potential for compression factors of x10 is tantalizing as data access and availability is a crucial aspect in high energy and nuclear physics analysis. We are even more so pleased to have had the support from and interest of the ROOT team lead. We intend to meet early in July to discuss the outstanding prospects this research could bring the community as a whole and how to integrate this technology as part of the ROOT package. Stay tuned for more exciting news on this topic...


Call for Summer Sunday Volunteers
(Gene Van Buren - BNL)

Dear fellow STAR Collaborators:

Each summer, there is an Open House of the RHIC facility for the public. This is part of the BNL "Summer Sundays" tour program series that has open houses for various BNL facilities through the summer.

This year's RHIC Summer Sunday will take place on Sunday, August 5th. This is a call for volunteers that will or can be at BNL on that date, and would like to give tours of STAR or otherwise speak with the public. Many visitors are very appreciative of the chance to see and learn what goes on in these otherwise-closed facilities. In addition to the opportunity to explain to a diverse but interested audience what STAR & RHIC are and what we do, volunteers get a free "Polo" type cotton shirt with the BNL logo, as well as a free brown bag lunch.

At the start of the day, we will review some talking points for the tours for first-time volunteers. So please do not feel that a lack of tour-giving experience should prevent you from participating.

The Lab admits people for these tours from 10 am in the morning until 3 pm in the afternoon. Out at STAR this means that we receive visitors from about 10:30 am until about 4:00 pm. We typically get on the order of 1000+ people who come through on these tours. To handle these crowds we usually try and have 8 to 10 tour guides present at STAR, and another person or two helping direct traffic flow.

If you would like to volunteer to help with these tours (even if only for part of the day) please send me an email. Please include in such an email what shirt size you would like (e.g. S, M, L, XL; this year the color will be a light red, as seen here), as well as any preference you have for the box lunch sandwich (tuna salad, chicken salad, Italian, turkey & swiss, ham & provolone, or a vegetable wrap). If you have any questions please feel free to contact me. You may also take a look at the recap article from last year's event.

Please consider helping out with what can be a rewarding few hours of your time!


Collaboration Members in the Headlines

Congratulations go out to the following STAR Collaboration Members:
Sevil Salur, Oleg Eyser, Frank Geurts, Sooraj Radhakrishnan, David Tlusty
Elected to the RHIC/AGS UEC:
  Sevil has been voted the Chair Elect and will become the Chair next year following STAR's own Rosi Reed (who also succeeds a STAR member in Jim Thomas, now the past chair). Sooraj and David have been voted as student/postdoc members with 1 year terms, while Oleg and Frank were elected as general members. STAR has several other members on the UEC; the member list can be found here.
Jim Drachenberg, Xiaofeng Luo, Takafumi Niida, Isaac Upsal
Recipients of the 2018 RHIC/AGS UEC Merit Awards:
  Jim: "for his exceptional contributions in measurements of pion-within-jet asymmetries from polarized pp collisions with STAR and his invaluable leadership in the roles of STAR deputy spokesperson and PWG convener" (more)
  Xiaofeng: "for his seminal contributions to the beam energy scan program at RHIC via first measurements of higher moments of net proton distributions with the STAR experiment" (more)
  Takafumi: "for his indispensable contributions to the measurements of local and global polarization and for his measurements of directed flow with differential femtoscopic techniques in heavy ion collisions with the PHENIX and STAR experiments" (more)
  Isaac: "for his indispensable contributions in the successful commissioning of the Event Plane Detector Upgrade for the STAR experiment and for his pioneering work which led to the first observation of global polarization in heavy ion collisions" (more)
Daniel Brandenburg
Quark Matter 2018 Ten Best Posters Award:
  Daniel's poster (advisor: Frank Geurts): Dimuon Invariant Mass Spectra with the Muon Telescope Detector at STAR in p+p collisions at 200 GeV
The authors of the ten best posters were given the opportunity to present their work in a flash talk of five minutes during the last plenary session. The ten selected authors can be found here. See Daniel's Quark Matter Summary earlier in this edition for additional details.
Jan Rusňák, Ting Lin
Recipients of the 2018 RHIC & AGS Thesis Awards:
  Jan's thesis (advisor: Jana Bielčíková): Jet Reconstruction in Au+Au collisions at RHIC
  Ting's thesis (advisor: Scott Wissink): Longitudinal double-spin asymmetries for di-jet production at intermediate pseudorapidity in polarized pp collisions at \sqrt(s) = 200 GeV
Jan and Ting presented their work in flash talks at the 2018 RHIC/AGS Users' Meeting (Jan & Ting), and their awards were featured in articles by their institutions as well (Jan & Ting). Their theses will be featured on the RHIC/AGS UEC's website (here).
Amani Kraishan
Recipient of the 2018 RHIC & AGS Users' Meeting Poster Award:
  Amani's poster (advisor: Bernd Surrow): Measurement Of Longitudinal Single-Spin Asymmetry For W Boson Production In Polarized Proton-Proton Collisions at STAR



STAR arts
(Levente Hajdu - BNL)

This is a feature for Collaborators to contribute something creative/artistic that relates to STAR. This could be a really cool looking graph generated from some analysis, or a striking photograph. The idea is akin to the "Back Scatter" feature of Physics Today (example), or the Picture of the Month of CERN Courier (example). Please feel free to have fun with this and consider making a contribution yourself for the next edition!



360° panoramic photo of the Wide Angle Hall centered on the STAR FMS (click on the image for a high resolution version)



Previous Edition: April 2018