Hypernuclear Spectroscopy at Jefferson Lab

Transcription

1 Hypernuclear Spectroscopy at Jefferson Lab Sabbatical project report submitted by Jörg Reinhold Associate Professor, Department of Physics Florida International University February 23, 2010 The core of the HKS collaboration, consisting of faculty and students from FIU, Hampton University and Tohoku University, together with technical staff from Hall C and the accelerator division in front of the newly installed experimental equipment. 1

2 Contents 1 Summary 3 2 The Project Physics Motivation: Significance of Hypernuclear Spectroscopy Prior work Sabbatical Project: Jefferson Lab Experiment E Publications Refereed Papers Presentations Invited Talks Talks and Posters Synergistic Activities 11 5 Mentoring 12 6 Research Grants/Funding 13 7 Outlook/Future Anticipated Activities 13 2

3 1 Summary From beginning of January 2009 through the end of December 2009 I was on sabbatical leave, which I spent at Jefferson Lab in Newport News, VA. My main activities there were focused on the installation and running of a hypernuclear spectroscopy experiment. As one of the four spokespersons of the experiment I represented the collaboration in interactions with lab management, coordinated and oversaw the installation and data acquisition period. Installation of the experiment began in mid March, followed by a two-month data acquisition period from end of August through beginning of November. During this time roughly 20 TB of data were collected from five different targets. The analysis of these data will take roughly two years and will be performed by four graduate students, one of them from FIU. Apart from managing and running the experiment, I mentored five FIU students who then in fall all presented results from their research at conferences. I gave four talks and one lecture. 2 The Project Most of the activities during my sabbatical were focused on preparing for and conducting an experiment in hypernuclear spectroscopy at Jefferson Lab in Newport News Virginia. The following three subsections will motivate the experiment and provide a timeline of the activities. More details about specific activities will be presented in Sections 3 6, followed by an outlook in Sec Physics Motivation: Significance of Hypernuclear Spectroscopy Ordinary nuclei are composed of protons and neutrons which in turn contain up and down quarks. In a hyperon, one of the original quarks is substituted by a strange quark. A hypernucleus contains a hyperon implanted as an impurity within the nuclear medium. Precise information about the mass and excitation energies of hypernuclei allows one to infer the underlying hyperon-nucleon interaction, which is not yet well known. Further, it is believed that some supernova explosions leave a neutron star as a remnant and that at least some regions in neutron stars are made up of matter containing strange quarks. A comprehensive set of hypernuclear data ultimately will also constrain current models of possible strange matter in stellar objects. Relatively little data is available for hypernuclei. Figure 1 shows the status before the experiment last summer. Until recently the field has been limited to a resolution of MeV in reaction spectroscopy employing secondary meson beams. At Jefferson Lab, the (e, e K + ) reaction can provide significantly better energy resolution, down to a few 100 kev. Further, an absolute calibration can be performed by the elementary p(e, e K + )Λ reaction. Thus, in contrast to planned γ-spectroscopy experiments at J-PARC, the (e, e K + ) reaction will allow to determine the absolute ground state masses of hypernuclei. See Ref. [1] for a recent review of hypernuclear spectroscopy. 3

4 Figure 1: Chart of hypernuclei studied before 2009 (from [1, 2]). Studies with (K,π) and (π,k) reactions were limited to 1.5 MeV resolution. Electroproduction experiments (green) for the first time can reach absolute measurements with sub-mev resolution. 2.2 Prior work As a postdoctoral scholar at Argonne National Laboratory, I managed the first strangeness electroproduction experiment at Jefferson Lab, E [3], in I conducted the second phase of this experiment as a spokesperson during my first year as faculty at FIU in That experiment was the first time ever, although with low resolution, that hypernuclei have been identified in kaon electroproduction [4, 5]. In Spring 2000, I joined the HNSS collaboration [6] that conducted the first systematic study of hypernuclear spectroscopy in electroproduction [7, 8]. The reputation gained during these first years at Jefferson Lab then led to an invitation to join the next generation experiments as a co-spokesperson of the emerging HKS collaboration. In January 2001, we successfully defended a new experiment proposal which was assigned the experiment number E [9, 10]. For this experiment, I led the design and construction of three segmented aerogel Čerenkov detectors by FIU students Michael Carl, Brian Beckford, Carlos Vega, Sean Grullon, Zolt Marcet, and Pavlo Baturin. My extensive experience at Jefferson Lab allowed me to take on a leading role during the 4-month data acquisition period in Summer The analysis is ongoing and preliminary results have been presented at several conferences, e.g. [11, 12]. As an extension of E01-011, a new proposal has been submitted to Jefferson Lab in Summer 2005 and, after peer review, been approved by PAC 28 [13] as experiment E [14]. 4

5 Figure 2: Layout of the HES/HKS experiment: Upon entering the hall, the beam is prebend by a so-called chicane and then is incident on the target at an angle with respect to the normal beam direction. The splitter magnet then bends scattered electrons and electroproduced kaons toward the HES and HKS spectrometers, respectively. Non-interaction beam electrons, the vast majority, are directed to the beam dump. The two Hall C standard spectrometers HMS & SOS were not in use. Only the SOS is shown on this drawing, rotated backward and partially blocking the entrance from the truck ramp. 2.3 Sabbatical Project: Jefferson Lab Experiment E Since the completion of our previous experiment in Fall 2005, the collaboration has been preparing for the new experiment. Funded by the Tohoku University group, a new electron spectrometer and a so-called splitter magnet have been fabricated in Japan and shipped to Jefferson Lab. FIU was responsible for the commissioning of the aerogel Čerenkov detectors that we have built for the previous experiment. We conducted cosmic ray tests of the detectors at Jefferson Lab. Also, we improved the magnetic shielding of the detector by an improved configuration of bucking coils. Prior to 2009, studies in preparation for this have been performed by FIU students Dalgis Mesa [15], Kelvin Rojas, Angel Nunez, and Christian Rovira. Apart from my general responsibilities as a spokesperson, I also worked on the layout of the experiment cabling, data acquisition electronics, and trigger system and the preparation of the experiment safety documentation. The following is a rough timeline of the activities: 5

6 Figure 3: View of the installed spectrometer system prior to closing the concrete shield bunkers. January 1, 2009: Left Miami for Jefferson Lab. January - March 2009: Final detector tests in JLab test areas; prepared detectors for move into the experimental area. April - August 2009: During this period, an entirely new spectrometer system was installed in Jefferson Lab s Hall C. This system consisted of a new beam line, a large dipole splitter magnet, the two high resolution spectrometers HES & HKS (several 100 tons each), the associated instrumentation, and several 100 tons of concrete shielding. Figure 2 shows a general outline of the experiment and Fig. 3 a picture of the almost completed setup. This was probably the single largest dedicated experiment installation at the lab since the initial construction with the standard hall equipment. The heavy lifting and construction activities were performed by technical staff from the hall and the accelerator division. Installation, adjusting, and cabling of the spectrometers particle detection systems was performed by the experiment collaboration. Throughout this period, I coordinated many of the collaboration s activities with hall staff. Further, I coordinated the cabling of the experiment, which involved the cutting, termination, and laying of several 1000 signal cables. Five students from FIU significantly contributed to this effort. Together with my students, I installed and commissioned the aerogel Cherenkov detectors for the experiment. A milestone of this effort was the successful test of the bucking coil system we had installed on the Cherenkov detectors in order to counteract the fringe magnetic field of the HKS spectrometer. 6

7 Figure 4: Coincidence timing between electron and kaon spectrometer (X-axis in ns and Y-axis in counts). The center peak is dominated by true coincidences, the satellite peaks by false coincidences originating from different beam bunches. September - October 2009: For a period of slightly more than two month the experiment ran 24 hours around the clock, seven days a week. Apart from my general responsibilities as a spokesperson, I acted as run coordinator, supervised junior members of the collaboration in their role as run coordinator, facilitated communication between experiment collaboration and lab/accelerator management, was responsible for data acquisition and trigger electronics, was on call through the entire period in case of problems with the equipment, guided students and postdocs in their online analysis efforts. Figures 4 and 5 show an online coincidence timing spectrum and a missing mass spectrum from the CH 2 calibration target. Hypernuclear spectra will become available after all calibration data will have been carefully analyzed. Table 1 gives an estimate of expected yields from the different targets. November - December 2009: Oversaw proper de-comissioning and storage of experimental equipment; start data analysis; attend international workshop in Rome to discuss future activities. December : Return to Miami. 3 Publications Projects like the one I engaged in last year are multiple year endeavors. After several years of preparation and last year spent on staging the experiment, we will now spend roughly two years analyzing the data. Therefore, papers that I co-authored during my sabbatical where the result of previous work and publications from the work conducted during the sabbatical will be forthcoming in roughly two to three years. During this time, I expect that I will 7

8 Figure 5: Missing mass spectrum for CH 2 target (X-axis is M miss M Λ in MeV, Y-axis is counts). The two peaks correspond to a Λ and a Σ hyperon in the final state. Eventually, the known masses of these two particles will allow an accurate calibration of the spectrometer system. Table 1: Expected yield for hypernuclear ground state events (g.s.). Cross section for quasi-free (QF) Λ production estimated as 0.2 A 0.8 µb/sr. Hypernulcear g.s. cross sections taken from [14] and [16]. Number of expected g.s. events estimated as #QF (g.s. crossection)/(qf cross section). Target # of QF Λ QF Λ cross section g.s. cross section #of g.s. events (observed) (estimated) (assumed) (estimated) 7 Li µb/sr 21 nb/sr Be µb/sr 4 nb/sr B µb/sr 21 nb/sr C µb/sr 112 nb/sr Cr µb/sr 69 nb/sr 210 8

9 present preliminary results at several conferences; for example, I have accepted an invited talk at the International Nuclear Physics Conference 2010 (INPC2010) that will be held July 4-9, 2010 in Vancouver, Canada. The International Nuclear Physics Conference is held every 3 years and brings together the worldwide community in the field of Nuclear Physics. I gave three invited and one contributed talk. The five FIU students that I mentored at JLab presented a total of 4 posters at a JLab symposium, 1 poster at an international conference, and 5 posters at a domestic conference. Another graduate student of mine, under my supervision, presented two talks at international conferences. Further, in recognition of our contributions to the field of hypernulcear spectroscopy, last year, Prof. Nakamura from Tohoku University and I accepted an invitation from Armand Faessler, the editor of Progress in Particle and Nuclear Physics, to write a review article on Electroproduction of Hypernuclei. This roughly 70-page article will be due in April Refereed Papers The following publications that appeared from January December 2009 are the result of previous work: 1. High Resolution Spectroscopy of 16N Λ by Electroproduction F. Cusanno... A. Acha... P. Baturin... P. Markowitz... B. A. Raue... J. Reinhold et al. Phys. Rev. Lett. 103, (2009) arxiv: [nucl-ex] 2. Neutral Pion Electroproduction in the Resonance Region at High Q 2 A. N. Villano... P. Markowitz... J. Reinhold et al. Phys. Rev. C 80, (2009) [arxiv: [nucl-ex]] 3. Applications of quark-hadron duality in F2 structure function S. P. Malace... W. U. Boeglin... P. Markowitz... J. Reinhold et al. [Jefferson Lab E Collaboration] Phys. Rev. C 80, (2009) [arxiv: [nucl-ex]] 4. Electroproduction of η Mesons in the S 11 (1535) Resonance Region at High Momentum Transfer M. M. Dalton... W. U. Boeglin... P. Markowitz... J. Reinhold et al. Phys. Rev. C 80, (2009) [arxiv: [hep-ex]] 3.2 Presentations Invited Talks 1. The Poor Man s RICH Concept: A One-Dimensional Dual Radiator RICH J. Reinhold, Hall C Summer Workshop, Jefferson Lab, August 6-7, 2009, Jefferson Lab. 9

10 2. From Glueing Borromean Nuclei to Softening Neutron Stars: Physics with Hyperons Joerg Reinhold, JMU Physics Department Seminar; James Madison University, Harrisonburg, Virginia; Thursday, 5 November Una breve storia della fisica nucleare strana nel Padiglione C del Laboratorio Jefferson Joerg Reinhold, The 2nd JSPS Core-to-core Seminar on Strangeness Nuclear Physics by Electron Beams, Istituto Superiore di Sanita, Rome, Italy, December 15, Talks and Posters 1. Application of Likelihood PID Method in Hypernuclear Experiment E Pavlo Baturin (presenter) and Joerg Reinhold, 3rd Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan; TuesdaySaturday, October 13 17, 2009; Waikoloa, Hawaii [BAPS.2009.HAW.CJ.9] 2. Commissioning and Calibrating Bucking Coil System for HKS Water Cerenkov Detector Victor Maxwell (presenter) and Joerg Reinhold, 3rd Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan; TuesdaySaturday, October 13 17, 2009; Waikoloa, Hawaii [BAPS.2009.HAW.GB.78]. 3. Calibration of Hypernuclear Missing Mass Spectra: Analysis of Various Target Effects Casey Neville and Joerg Reinhold (Florida International University) 76th Annual Meeting of the Southeastern Section of APS Wednesday Saturday, November 11 14, 2009; Atlanta, Georgia. [BAPS.2009.SES.LA.24] 4. Commissioning and Calibrating Bucking Coil System for HKS Water Cerenkov Detector Victor Maxwell and Joerg Reinhold (Florida International University) 76th Annual Meeting of the Southeastern Section of APS Wednesday Saturday, November 11 14, 2009; Atlanta, Georgia. [BAPS.2009.SES.LA.25] 5. Calibration Procedure of the HKS Time-Of-Flight System Rafael Badui and Joerg Reinhold (Florida International University) 76th Annual Meeting of the Southeastern Section of APS Wednesday Saturday, November 11 14, 2009; Atlanta, Georgia. [BAPS.2009.SES.LA.26] 6. An active magnetic field compensation system for the HKS aerogel Cherenkov detectors Angel Nunez and Joerg Reinhold (Florida International University) 76th Annual Meeting of the Southeastern Section of APS Wednesday Saturday, November 11 14, 2009; Atlanta, Georgia. [BAPS.2009.SES.LA.27] 10

11 7. The Jefferson Lab E Hypernuclear Spectroscopy Experiment Jason Bono and Joerg Reinhold (Florida International University) 76th Annual Meeting of the Southeastern Section of APS Wednesday Saturday, November 11 14, 2009; Atlanta, Georgia. [BAPS.2009.SES.LA.28] 8. The Jefferson Lab Hall C Hypernuclear spectroscopy program Joerg Reinhold (Florida International University) 76th Annual Meeting of the Southeastern Section of APS Wednesday Saturday, November 11 14, 2009; Atlanta, Georgia. [BAPS.2009.SES.NB.3] 9. Spectroscopy of Λ Hypernuclei in the (e,e K + ) Reaction at Jefferson Lab Pavlo Baturin (Florida International University) for the E (HKS) Collaboration (Hall C, Jefferson Lab), XIII International Conference on Hadron Spectroscopy, Florida State University, November 29 December 4, Synergistic Activities I presented a lecture with the title Nuclear Physics Experiment, an Example during the Summer 2009 Introduction to Experimental Nuclear Physics Lecture Series at Jefferson Lab. This lecture was attended by roughly 30 student summer interns at Jefferson Lab, including the four FIU undergraduate students that I was able to place into the program. For a group of roughly 15 students from FIU, Hampton University, Xavier University (LA), and Tohoku University (Japan), I organized a tour the new Hampton University Proton Therapy Institute (HUPTI). As one of the spokespersons of the experiment, I was the main contact for JLab s public affairs office. As a result, I gave several tours to visiting groups of the Hall C facilities: Department of Energy Science and Technology Review Panel, July 15, Rappahannock Community College Professors Tour, July 30, A tour for two officials from the DOE Office of Counterintelligence, Monday, November 16. Tour for VIP guests from the Women in Science and Engineering Round table discussion, Tuesday, Nov 17. Tour for a group of visitors from KEK, Japan, Nov 17. Tour for local engineering association: American Society of Mechanical Engineers Eastern Virginia - District F ( Nov. 17, I gave an interview to the Jefferson Lab Public Affairs Office, which resulted in an article prominently posted as a Jefferson Lab Front Page News Story. [ 11

12 Figure 6: FIU Team in front of HES spectrometer inside Jefferson Lab s Hall C. From left to right: Jason Bono, Victor Maxwell, Angel Nunez, Joerg Reinhold, Casey Neville, Raphael Badui (picture taken by Greg Adams, Public Affairs, JLab). 5 Mentoring Five FIU students were directly involved in the project (see Fig. 6): All students presented their work at conferences in Fall Victor Maxwell was supported by a SULI internship for 10 weeks in summer After his internship, Victor continued to work on the project through mid December, supported by my grant. He participated in the entire commissioning and data acquisition phase. He presented results from his research at JLab Symposium, DNP 2009, SESAPS Angel Nunez, Casey Neville, Rafael Badui were supported by the FaST program. They spend 10 weeks at Jefferson Lab during summer During this time they were involved in the testing of detectors, the installation of the instrument,... All three presented posters at the JLab Symposium and subsequently at the SESAPS conference in Atlanta (see publications) Jason Bono joined my group in Summer 2009 as a new graduate student. He stayed at Jefferson Lab through end of November and participated in all aspects of the project. He will analyze data of the experiment as part of his Ph.D. thesis. He presented a poster at the SESAPS conference in Atlanta (see publications). Marianna Gabrielyan, Pavlo Paturin, Hari Khanal, Diane Schott, all FIU graduate students working on different thesis projects, participated in the commissioning 12

13 and data acquisition phases. Their contributions will earn them co-authorship on future publications from the project. Further, I worked closely together with my colleagues students, Atushi Chiba, Ayako Shichijo Chunhua Chen, Daisuke Doi, Daisuke Kawama, Sho Nagao, Toshiyuki Gogami, Xiyu Qiu, and Zhihong Ye. 6 Research Grants/Funding This sabbatical was partly supported by a grant from Jefferson Lab, FIU Project ID , and the JSA/JLab Sabbatical and Research Leave Support Program. I continued in my role as PI and project manager of Department of Energy award # DE-FG02-99ER41065, Nuclear Physics Research at Jefferson Lab. This grant supported the Jefferson Lab related research activities of four faculty, one postdoc, and six graduate students. In February 2009, two colleagues from Hampton University, Drs. Michael Kohl and Liguang Tang, and I submitted a pre-proposal to the NSF PIRE solicitation, NSF # The pre-proposal was accepted. In September 2009, we submitted the full proposal, Start of a New Era: The Use of Intense Kaon Beams at J-PARC for Fundamental Studies of Nuclear and Particle Physics, NSF # Unfortunately, this proposal just recently was declined. In April 2009, I submitted an application to the Faculty and Student Teams (FaST) Program, a cooperative effort between the Department of Energy (DOE) Office of Science and the National Science Foundation (NSF). The application was successful and supported 10-week research internships at Jefferson Lab for FIU undergraduate students Angel Nunez, Casey Neville, and Raphael Badui. 7 Outlook/Future Anticipated Activities The proposed project is part of a long term program in hypernuclear spectroscopy. The analysis of the data collected during my sabbatical will take roughly two years. Four students, one each from Tohoku University and FIU (Jason Bono) and two from Hampton University are expected to receive their Ph.D.s as a result of this analysis. The upgrade of the electron spectrometer, funded by the Japanese collaborators, was specifically undertaken to keep the experiment compatible with beam conditions after the planned upgrade of the Jefferson Lab accelerator ( ). Further, I already joined two of the first generation experiments [17, 18] that have been approved for the new J- PARC facility in Japan [19]. These experiments will be complementary to our Jefferson Lab projects. I plan to seek funding for the J-PARC projects during the next year, when I need to renew the current DoE grant. Previously, we proposed a new experiment at Jefferson Lab [20] which received a high scientific rating of A- [21]. The remaining time does not allow to schedule this experiment 13

14 before the planned upgrade of Jefferson Lab. However, just in December 2009, we submitted a new request to the Jefferson Lab Program Advisory Committee. We requested approval for a test of a the experimental method to be conducted in The PAC conditionally approved this request. Final scheduling is now subject to lab management decisions. In summer 2012, Jefferson Lab will shut down the experimental program for roughly one year in order to upgrade the accelerator facility to 12 GeV beam energy. During this time, I anticipate an increased effort in R&D projects in support of the new experimental equipment necessary to utilize the upgraded accelerator. For example, I am a collaborator of the GlueX experiment, one of the key experiments that will be conducted after the upgrade. With FIU faculty Dr. Werner Boeglin in the lead, Boeglin and I drafted an MoU with Jefferson Lab for the construction of the start counter for the GlueX experiment. I also started discussions with Dr. Tanja Horn from Catholic University In Washington DC to join her next MRI proposal as a sub awardee. Together we plan to build the aerogel Cherenkov detectors for the new Super High Momentum Spectrometer in Jefferson Lab s Hall C. All the efforts related to the upgrade will again provide excellent opportunities for FIU student involvement. 14

15 References [1] O. Hashimoto and H. Tamura, Prog. Part. Nucl. Phys. 57, 564 (2006). 3, 4 [2] O. Hashimoto and S.N. Nakamura, Tohoku University, Sendai, Japan (private comminucation). 4 [3] Jefferson Lab experiment E91-016: Electroproduction of Kaons and Light Hypernuclei, spokespersons J. Reinhold and B. Zeidman 4 [4] F. Dohrmann et al., Phys. Rev. Lett. 93, (2004) [arxiv:nucl-ex/ ]. 4 [5] F. Dohrmann et al., Phys. Rev. C 76, (2007) [arxiv: [nucl-ex]]. 4 [6] Jefferson Lab experiment E89-009: Investigation of the Spin Dependence of the ΛN Effective Interaction in the p Shell, spokespersons R. Chrien, E. Hungerford, L. Tang 4 [7] T. Miyoshi et al. [HNSS Collaboration], Phys. Rev. Lett. 90, (2003) [arxiv:nuclex/ ]. 4 [8] L. Yuan et al. [HNSS Collaboration], Phys. Rev. C 73, (2006) [arxiv:nuclex/ ]. 4 [9] Jefferson Lab Program Advisory Committee (PAC 19), January 31 - February 2, [10] Jefferson Lab experiment E01-011: Spectroscopic Study of Lambda Hypernuclei Up To Medium-Heavy Mass Region Through the (e,e K + ) Reaction, spokespersons O. Hashimoto, S.N. Nakamura, J. Reinhold, L. Tang 4 [11] Spectroscopy of light to medium mass Lambda hypernuclei, Joerg Reinhold, contributed talk at PANIC05, Particles and Nuclei International Conference, Santa Fe, NM - October 24-28, [12] Spectroscopy of Lambda-Hypernuclei in the (e,e K + ) Reaction at Jefferson Lab Joerg Reinhold, invited talk presented at the 9th Conference on the Intersections of Particle and Nuclear Physics (CIPANP 2006), Rio Grande, Puerto Rico, May 30-June 3, [ 4 [13] Jefferson Lab Program Advisory Committee (PAC 28), August 23-26, [14] Jefferson Lab experiment E05-115: Spectroscopic Investigation of Λ Hypernuclei in the Wide Mass Region using the (e,e K + ) Reaction, spokespersons O. Hashimoto, S.N. Nakamura, J. Reinhold, L. Tang 4, 8 [15] Magnetic Field Reduction in Photomultipliers with the use of Bucking Coil, Dalgis Mesa (FIU undergraduate student) and Joerg Reinhold, 2007 APS April Meeting, Saturday Tuesday, April 14 17, 2007; Jacksonville, Florida, Bulletin of the American Physical Society, Volume 52, Number 3., 2007, American Physical Society 5 15

16 [16] M. Sotona and S. Frullani, Prog. Theor. Phys. Suppl. 117, 151 (1994). 8 [17] J-PARC 50-GeV PS Experiment E05, Spokesperson: T. Nagae (KEK, Japan) 13 [18] J-PARC 50-GeV PS Experiment E13, Spokesperson: H. Tamura (Tohoku U., Japan) 13 [19] Program Advisory Committee (PAC) for Nuclear and Particle Physics Experiments at the J-PARC 50GeV Proton Synchrotron 1st PAC meeting: Fri 30 June - Sun 02 July, [20] Jefferson Lab proposal PR08-112: Study of Light Hypernuclei by Pionic Decay at JLab, spokespersons O. Hashimoto, A. Margaryan, S.N. Nakamura, J. Reinhold, L. Tang; presented to PAC33 on January 16, 2008 [ prog/pacpage/pac33/] 14 [21] Jefferson Lab Program Advisory Committee (PAC 33), January 14-18,