Bulletin of the American Physical Society
2020 Fall Meeting of the APS Division of Nuclear Physics
Volume 65, Number 12
Thursday–Sunday, October 29–November 1 2020; Time Zone: Central Time, USA
Session DH: Mini-Symposium: Hyper Nuclear Spectroscopy I |
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Chair: Joerg Reinhold, FIU |
Friday, October 30, 2020 8:30AM - 9:06AM |
DH.00001: A possible observation of $\Lambda $nn continuum structure and a bound $\Sigma $NN state using the (e,e'K$^{\mathrm{+}})$ reaction. Invited Speaker: Liguang Tang A mass spectroscopy experiment with a pair of nearly identical high resolution spectrometers and a tritium target was performed in Hall A at Jefferson Lab. Utilizing the (e,e'K$^{\mathrm{+}})$ reaction, two possible $\Lambda $nn resonance states and a bound $\Sigma $NN state were observed for the first time with an energy resolution of better than 1.6 MeV (FWHM), although greater statistics are needed to make definitive identifications. The energy resolution is the best ever reported for reaction mass spectroscopy involving A $=$ 3 hypernuclei. The experimentally measured $\Lambda $nn states can provide constraints in describing the $\Lambda $n interaction, for which no scattering data exist. Moreover, although bound A $=$ 3 and 4 $\Sigma $ hypernuclei have been predicted, only an A $=$ 4 $\Sigma $ hypernucleus ($^{\mathrm{4}}_{\mathrm{\Sigma }}$He) has been found, utilizing the (K$^{\mathrm{-}}$, $\pi^{\mathrm{-}})$ reaction on a He target. A possibility to study on a $\Sigma $NN bound is also discussed and the observed state in this experiment is likely to be a $\Sigma ^{\mathrm{0}}$nn state. The experiment proves the uniqueness of the (e,e'K$^{\mathrm{+}})$ reaction with the Tritium target using the CEBAF beam. The experiment needs to be repeated again with the optimized experimental configuration in order to achieve the needed statistics that is necessary to make solid confirmation and obtain the needed precision on the measurement on the binding energy and natural width of these states. [Preview Abstract] |
Friday, October 30, 2020 9:06AM - 9:18AM |
DH.00002: A possible observation of Λnn continum structure and bound ΣNN structure by using the 3H(e,e’K+)Λnn reaction Bishnu Pandey The E12-17-003 Experiment was carried out successfully at Jefferson lab in 2018 by considering tritium as production target. By utilizing the Hall A high resolution spectrometers and the 3H(e,e’K+)Λnn reaction, two possible Λnn resonance states and a ΣNN bound state were observed with an energy resolution of about 1.6 MeV (FWHM), although the statistics is not enough to solidly conform the observed states. This presentation will give description of this experiment, its analysis, and results. [Preview Abstract] |
Friday, October 30, 2020 9:18AM - 9:30AM |
DH.00003: Lambda Hypertriton Spectroscopy by Electron Scattering at JLab Toshiyuki Gogami The simplest bound system with a $\Lambda$ hyperon is a hypertrion which is an isospin singlet state of three body system. The strong interaction between a $\Lambda$ and a nucleon ($\Lambda N$ interaction) has been mainly investigated by using energies of $\Lambda$ hypernuclei. The $\Lambda$ binding energy $B_{\Lambda}$ of the simplest hypernuclei could give us a strong constraint for the study of $\Lambda N$ interaction. We are planning to measure the $\Lambda$ binding energy with an accuracy of $|\Delta B_{\Lambda}^{\rm total}|<100~{\rm keV}$ which would be the best accuracy among counter experiments. In the presentation, I will introduce an overview of the experiment (JLab C12-19-002). An expected result and impact for the baryon interaction study will also be discussed. [Preview Abstract] |
Friday, October 30, 2020 9:30AM - 9:42AM |
DH.00004: Status of the experiment of Lambda-n interaction measrement via FSI egffect in gamma+d reaction at ELPH, Tohoku Univ. Masashi Kaneta, Takeru Akiyama, Hiroyuki Fujioka, Tomomasa Fujiwara, Kenji Fukada, Kousuke Itabashi, Masaya Mizuno, Sho Nagao, Satoshi N. Nakamura, Yuki R. Nakamura, Kazuki Okuyama, Yuichi Toyama, Keita Uehara, Hiroo Umetsu Hypernuclear spectroscopy is one of the most powerful tools to extract Hyperon-Nucleon interaction. On the other hand, recent studies of $^{4}_{\Lambda}$H and $^{4}_{\Lambda}$He show that there is a larger difference of binding energies between the two light hypernuclei than theoretical calculation. The problem is called charge symmetry breaking in $\Lambda$-$N$ interaction. It means that there is difference between $\Lambda$-$p$ and $\Lambda$-$n$ interactions or the other effect. There are data about $\Lambda$-$p$ scattering, but no data about $\Lambda$-$n$ scattering due to difficulty of the experiment. One of the keys to solve the problem is to measure $\Lambda$-$n$ with enough statistics. We proposed the experiment to obtain $\Lambda$-$n$ interaction via final-state-interaction effect in $\gamma + d \rightarrow K^{+} + \Lambda + n$ reaction at ELPH, Tohoku University. We will present the status of the experiment including the detector development in this talk. [Preview Abstract] |
Friday, October 30, 2020 9:42AM - 9:54AM |
DH.00005: Differential cross section of the $p(e,e'K^{+})\Lambda/\Sigma^{0}$ reaction at $Q^{2}\simeq0.5$ [(GeV/$c$)$^{2}$] Kazuki Okuyama, Franco Garibaldi, Pete Markowitz, Satoshi Nakamura, Joerg Reinhold, Liguang Tang, Guido Urciuoli We have performed high resolution mass spectroscopy of hypernuclei with the $(e,e'K^{+})$ reaction using the high intensity electron beam of CEBAF at Thomas Jefferson National Accelerator Facility (JLab). Although hyperons electroproduction elementary process at low $Q^2$ is indispensable for the hypernuclear research, both quality and quantity of data in forward angles are far from satisfactory. In the $(e,e'K^{+})$ reaction, protons are converted into hyperons, so this makes it possible to measure the cross section of the $p(e,e'K^{+})\Lambda/\Sigma^0$ reaction on a gas H$_{2}$ target. We deduced the differential cross section of the $p(e,e'K^{+})\Lambda/\Sigma^0$ reaction with calibration data of the latest hypernuclear experiment (JLab E12-17-003). These data were collected at Experimental Hall A using two high-resolution magnetic spectrometers, HRS's, and we measured the momentum vectors of the kaons and scattered electrons. They correspond to data sets of $W\simeq3.0$ [GeV] and $Q^2\simeq0.5$ [(GeV/$c$)$^{2}$]. In this presentation, I will report the result of the analysis for the $p(e,e'K^{+})\Lambda/\Sigma^{0}$ reaction. [Preview Abstract] |
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