Experimental Study of Hypernuclei Electroproduction by High Precision Spectroscopy

Experimental Study of Hypernuclei Electroproduction by High Precision Spectroscopy
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Release: 2009
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Jlab experiment E01-011, carried out in 2005 in JLab Hall C, is the second generation of the hypernuclear spectroscopy experiments by the (e, e'K+) reaction. The (e, e'K+) reaction is complimentary to the associated production reactions (K-, [pi]- ), ([pi]+, K+) since, due to a larger momentum transfer to a hyperon, excitations of both spin-non-flip and spin-flip states are possible. The experiment uses high quality and continuous primary electron beam to produce neutron rich hypernuclei on various targets by the electroproduction. The experimental setup consists of splitter magnet, high resolution kaon spectrometer (HKS) and electron spectrometer (Enge) implemented in new configuration, the so called 'Tilt Method'. Production data was taken on multiple targets: CH2, 6Li, 7Li, 9Be, 10B, 12C and 28Si. In present study the analysis of CH2, 12C and 28Si is presented. The elementary processes of p(e, e'K+)[Lambda]/[Sigma] from CH2 data were used for calibration of the spectrometer optics and kinematics. The hypernuclear spectra of 12[Lambda]B was obtained with ground state resolution of 0.47 ± 0.07 MeV (FWHM), the best ever achieved. Feasibility of the electroproduction reaction to study medium to heavy targets has been proven with the first high resolution beyond p-shell hypernuclear spectra from 28[Lambda]Al hypernuclei. The obtained results of the E01-011 experiment confirmed that hypernuclear spectroscopy by the (e, e'K+) reaction is a very useful technique.

Recent Results on High Resolution Hypernuclear Spectroscopy by Electroproduction at Jefferson Lab, Hall A.

Recent Results on High Resolution Hypernuclear Spectroscopy by Electroproduction at Jefferson Lab, Hall A.
Author: G. Chang
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Release: 2005
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The first ''systematic'' study of 1 p shell hypernuclei with electromagnetic probes has started in Hall A at Jefferson Lab . The aim is to perform hypernuclear high resolution spectroscopy by the electroproduction of strangeness on four 1p-shell targets: 12C, 9Be, 16O, 7Li. The first part of the experiment on 12C and 9Be has been performed in 2004, the second part (16O and 7Li) is scheduled for June 2005. To overcome the major experimental difficulties, namely the low counting rate and the challenging Particle IDentification (PID), two septum magnets and a Ring Imaging CHerenkov (RICH) detector had to be added to the existing apparatus. After underlining the particular role the electroproduction reaction plays in hypernuclear physics we describe the challenging modifications of the Hall A apparatus. Preliminary results on 12C and 9Be are presented.

High Precision Spectroscopy of Lambda-Hypernuclei by (e, E' K) Reaction and Gamma-ray Measurement

High Precision Spectroscopy of Lambda-Hypernuclei by (e, E' K) Reaction and Gamma-ray Measurement
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Release: 2001
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Hypernuclei, with one nucleon converted into a hyperon and coupled back to the residual nuclear core, provide a new probe to study the hyperon-nucleon interaction and an additional strangeness degree of freedom to test the limit of our conventional nuclear models in solving the many body system. The First Lambda electroproduction experiment E89009(HNSS) at JLAB focusing on the Lambda hypernuclear spectroscopy in p-shell achieved the best resolution(FWHM: 500-600 keV) ever reached in this field. The unnatural parity (spin-flip) states were observed for the first time on the 12 / Lambda B missing mass spectrum. The detailed hypernuclear structure of 9 / Lambda Be produced through (k−, pi−) reaction in BNL-AGS, was studied with the hypernuclear gamma-ray spectroscopy by using a large acceptance germanium detector (Hyperball) in experiment E-930.

Hypernuclear Physics Programs Via Electroproduction in Hall C at Jefferson Lab

Hypernuclear Physics Programs Via Electroproduction in Hall C at Jefferson Lab
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Release: 1998
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Hypernuclei with strangeness -1 have been intensively studied both theoretically and experimentally using hadronic probes and reactions, (K, [pi]) and ([pi], K), for many years since the first discovery of such formation in the earlier nuclear emulsion and bubble chamber experiments. Many recent review papers exist on the status of hypernuclear physics, such as the recent one written by B.F. Gibson and Ed V. Hungerford in which one can find detailed discussion on all aspects of hypernuclear physics and more complete reference list. The unique feature of this field can be summarized, in general, into three categories: (1) Strong Interaction Involving Strangeness, (2) Weak Interaction with [Delta]S = -1, and (3) Medium Modifications. For strong interaction, it is commonly believed that a hyperon can be treated as an ''impurity'' to probe deep interior of the nuclear medium to explore fundamental issues such as the changes in size and shape due to the short range feature of YN interactions, limit of conventional nuclear model (shell or cluster) in solving for many body systems with new degree of freedom, spin dependent forces (spin-spin, spin-orbital, tensor), new symmetry and explicit QCD effect in nuclear media. Many of such issues are impossible or very difficult to be studied in the ordinary nuclear physics. The keys for success in this part of field includes good energy resolution and wide ranged spectroscopy. Until now, many important issues are still unresolved or remained to be resolved in more consistent and satisfactory fashion, such as spin dependent forces. This is due to luck of high quality experimental facilities. Recent experiments at KEK using ([pi], K) reaction with a dedicated new SKS spectrometer have demonstrated the importance of improving the energy resolution. New structures were found as resolution improved only from 3 MeV to 2 MeV.

High Resolution Spectroscopy of 12B_Lambda by Electroproduction

High Resolution Spectroscopy of 12B_Lambda by Electroproduction
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Release: 2007
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An experiment measuring electroproduction of hypernuclei has been performed in Hall A at Jefferson Lab on a $^{12}$C target. In order to increase counting rates and provide unambiguous kaon identification two superconducting septum magnets and a Ring Imaging CHerenkov detector (RICH) were added to the Hall A standard equipment. An unprecedented energy resolution of less than 700 keV FWHM has been achieved. Thus, the observed \lam{12}{B} spectrum shows for the first time identifiable strength in the core-excited region between the ground-state {\it s}-wave $\Lambda$ peak and the 11 MeV {\it p}-wave $\Lambda$ peak.

Proceedings of The IX International Conference on Hypernuclear and Strange Particle Physics

Proceedings of The IX International Conference on Hypernuclear and Strange Particle Physics
Author: Josef Pochodzalla
Publisher: Springer Science & Business Media
Total Pages: 400
Release: 2008-06-27
Genre: Science
ISBN: 3540763678
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This volume contains the proceedings of the IX International Conference on Hypernuclear and Strange Particle Physics (HYP 2006). This conference series is devoted to the progress of our knowledge about strangeness flavor in hadron and nuclear physics. Besides the traditional topics such as hadron structure, hypernuclear spectroscopy and weak decay of hypernuclei, a particular focus of this conference was on the properties of strange mesons and their binding in nuclear systems.

Update of High Resolution (e, E'K^+) Hypernuclear Spectroscopy at Jefferson Lab's Hall A.

Update of High Resolution (e, E'K^+) Hypernuclear Spectroscopy at Jefferson Lab's Hall A.
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Release: 2010
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Updated results of the experiment E94-107 hypernuclear spectroscopy in Hall A of the Thomas Jefferson National Accelerator Facility (Jefferson Lab), are presented. The experiment provides high resolution spectra of excitation energy for 12B_\Lambda, 16N_\Lambda, and 9Li_\Lambda hypernuclei obtained by electroproduction of strangeness. A new theoretical calculation for 12B_\Lambda, final results for 16N_\Lambda, and discussion of the preliminary results of 9Li_\Lambda are reported.

Feasibility Test Run of C-12(e, E'K[sup +] Reaction at Thomas Jefferson National Accelerator Facility

Feasibility Test Run of C-12(e, E'K[sup +] Reaction at Thomas Jefferson National Accelerator Facility
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Release: 2004
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The high quality and high duty factor (100%) electron beam at Jefferson Lab offers an opportunity to broaden their view of hypernuclear physics by studying the (e, e[prime]K[sup +]) reaction with high resolution. The present data represent a feasibility study of such a reaction on a carbon target. The test run was carried out during experiments E91-16 (Electroproduction of Kaons and Light Hypernuclei) and E93-18 (Kaon Electroproduction on p(e, e[prime]K[sup +])Y). These two experiments used liquid deuterium and hydrogen targets, respectively. There exist data on an aluminum target for the background calibration of the liquid targets which are suitable also for a feasibility study of electroproduction of hypernuclei. These data are still under analysis. The goal of this test run is to evaluate issues concerned with the electroproduction of hypernuclei. These issues include: (1) the quasi-free production rate, which had not been measured previously, (2) random coincidence background, (3) keon identification over a possibly large hadronic background, and (4) possible evaluation of the production rate of the bound hypernuclear structures. This test run will supply significant knowledge for running high quality hypernuclear experiments at Jefferson Lab. The spectroscopy of hypernuclei has been studied mainly in two ways: the strangeness-exchange reaction (K[sup -], [pi][sup -]), and associated strangeness production ([pi][sup +], K[sup +]). The (e, e[prime]K[sup +]) reaction has the advantage of exciting both natural- and unnatural-parity states and the possibility of obtaining good energy resolution. The cross section for the (e, e[prime]K[sup +]) reaction is about a hundred times smaller than for the corresponding hadronic production reactions but it is compensated for by the availability of high intensity and high duty factor electron beams. In order to optimize the production rate, the kinematic setting requires both the scattered electron and kaon to be detected at very forward angles. The test run was not optimized for hypernuclear production, but it serves as an important technical evaluation for future hypernuclear programs at Jefferson Lab. The first high-resolution spectroscopy experiment on p-shell lambda hypernuclei is tentatively scheduled to run in 1999 in Hall C at Jefferson Lab.

Strangeness Nuclear Physics - Proceedings Of The Apctp Workshop (Snp '99)

Strangeness Nuclear Physics - Proceedings Of The Apctp Workshop (Snp '99)
Author: Il-t Cheon
Publisher: World Scientific
Total Pages: 462
Release: 2000-09-27
Genre: Science
ISBN: 9814492752
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The unique role of strangeness in nuclear physics has recently attracted much attention, from both the theoretical and experimental viewpoints. This is due not only to the broad spectrum of possible hadron many-body systems with strangeness, but also to the fact that strangeness gives us an opportunity to study fundamental baryon-baryon interactions in a new perspective. Our knowledge of this subject has widened as the scope of hypernuclear experiments has expanded from strangeness exchange and the associated production reactions to hypernuclear weak decays, β decays, cascade hypernuclei, double-Λ events, electroproduction of strangeness, etc. This trend will be accelerated by the full operation of new laboratories such as TJLab, COSY, DAΦNE, JHF, MAMI, and others. Various aspects of those important and exciting topics are discussed in this book in order to get a perspective of this fast developing area of nuclear physics.