SN0708 : Recommendations of the 2018 Nuclear and Particle Physics Program Advisory Committee

Author(s):NPP Program Advisory Committee
Date:Jun. 8, 2018
File(s): BNL PAC 2018 Recommendations - FINAL.pdf

 Executive Summary

The Program Advisory Committee (PAC) convened on June 7 – 8, 2018, to evaluate the STAR Beam Use Request for Runs 19 and 20 and comment on the overall RHIC program. The PAC was presented with the status of ongoing analysis efforts and publications from the STAR, PHENIX and RHICf research programs. The PAC heard a status report on the STAR upgrades for the Beam Energy Scan II and STAR Plans for physics beyond the beam energy scans. In addition, presentations were made on the performance of RHIC during Run-18, a status report on the science program and progress in sPHENIX, an update of the proposed science program for an EIC detector based on sPHENIX, the Coherent electron Cooling Proof of Principle Experiment, and a report on the status and the prospects for the Low Energy RHIC electron Cooling (LEReC).

The PAC thanks the collaborations for their work and presentations, and the collaborations and CA-D for their input and cooperation in responding to questions. We commend CA-D and STAR for the success of Run 18. The performance of RHIC was outstanding during the isobar run. STAR is congratulated for the successful installation of the EPD, fixed-target program, and the iTPC sector test, which positions STAR to be able to pursue the BES-II goals. The PAC places highest priority on accomplishing the BES-II program. Within this program highest priority running should be placed on the 7.7 GeV collider run. We commend the CA-D for bringing LEReC to the state of the art that it is today and the highest priority for CAD and RHIC for the coming year is the commissioning and successful operation of LEReC. We look forward with anticipation to the results of the BES-II with the 2019, 2020, and 2021 runs.

The PAC commends both the PHENIX and the STAR collaboration for maintaining outstanding scientific productivity in terms of the number of papers published, the number of Ph.D. graduates, and the high impact of papers in the nuclear physics community. The PAC is pleased to see the continued success in utilizing CORI resources to manage the computing operations, and the implementation of the compact data format (picoDST) in STAR. We are pleased to see STAR’s progress on understanding the corrections for the detector response in the net-proton cumulant measurement. We strongly encourage the STAR collaboration to pursue the completion of these studies with the highest priority to enable the timely publication of these important BES-I results.

STAR presented a rich program for future operation after BES II that addresses many important and innovative topics in p+p, p+A and A+A physics. The most interesting of these is focused on forward physics that would be made possible by a forward upgrade covering rapidities up to 4.2 with $5.3 M further investment, and would enable studies of novel reaction channels including several specific diffractive reactions and ultra-peripheral collisions of interest to hadron structure and QGP physics alike. Hadron structure measurements, such as diffractive dijet production, are highly relevant for the physics to be investigated at EIC, both for their e+p and e+A components, and may help to further sharpen the EIC physics case. From the heavy-ion perspective, QGP vorticity and Lambda polarization measurements in peripheral collisions would address vorticity generation at the microscopic level. Several international groups have submitted or are ready to submit proposals to finance most of the needed cost-efficient forward hardware upgrades. We commend STAR for developing and sharpening this option, which enriches the range of future opportunities for BNL. However, to realize a significant fraction of this program, multi-year running will be necessary. We urge the directorate to decide within this year whether the realization of these plans is realistic. A timely analysis of the 2017 data with transverse polarization could set the pace for the data analysis of possible STAR running after BES II and should be given high priority.

The PAC congratulates the sPHENIX collaboration for their successful CD1/3A review and their recruitment of new institutions that are pursuing funding opportunities to restore the full configuration of the EMCal. We encourage the collaboration to aggressively find resources that enable the inclusion of the MVTX vertex detector, which is essential for the open heavy-flavor program. We are also encouraged by the progress in the detector development and simulations in sPHENIX. The PAC was pleased to see that the sPHENIX detector may also serve, after suitable upgrades, as a very capable EIC detector.

The PAC congratulates the Low Energy RHIC electron Cooling (LEReC) group and the CA-D for recent progress in commissioning of the electron beam for the LEReC cooler and for bringing LEReC to its current state with use of state of the art methods and technologies. It will be the first RF-based electron cooler with bunched beams for collider operation. The PAC considers the commissioning and successful operation of LEReC as the highest priority in 2019 and 2020 for CA- D and RHIC. This is critical for operation of RHIC in the 7.7 GeV collider mode and essential for accomplishing the BES-II program. The PAC was presented a beam use request for a proof-of- principle experiment for Advanced Coherent electron Cooling (ACeC) in Run 20. If successful, the proposed ACeC could provide strong hadron cooling for a future EIC. The goals for the current tests, which were to conclude shortly after our meeting, are to reliably imprint a RHIC ion-beam signature into the electron beam by establishing a transverse overlap of the two beams and to observe CeC cooling of the ion beam. The ACeC team is to be congratulated for its progress and encouraged to continue development of ACeC techniques to the extent CeC becomes a viable candidate for use in an EIC. We look forward to hearing the results of the Run 18 tests and will consider a proposal for ACeC tests during Run 20 at our meeting next year.

Keywords:BUR, PAC