Hypernuclear spectroscopy using the(e,e'K+)reaction

Abstract

A pioneering experiment in Λ hypernuclear spectroscopy, undertaken at the Thomas Jefferson National Accelerator Facility (Jlab), was recently reported. The experiment used the high-precision, continuous electron beam at Jlab, and a special arrangement of spectrometer magnets to measure the spectrum from nat C and 7 Li targets using the (e, e ′ K + ) reaction. The 12 Λ B spectrum was previously published. This experiment is now reported in more detail, with improved results for the 12 Λ B spectrum. In addition, unpublished results of the 7 Λ He spectrum are also shown. This later spectrum indicates the need for a more detailed few-body calculation of the hypernucleus and the reaction process. The success of this experiment demonstrates that the (e, e ′ K + ) reaction can be effectively used as a high resolution tool to study hypernuclear spectra, ant its use should be vigorously pursued.

Superconducting phase diagram of itinerant antiferromagnets

“…The intraband (Γ kk ) and interband (Γ kk ) pairings must be expressed in the singlet and triplet symmetrized versions in accordance with Eqs. (17)- (18). The largest eigenvalue, λ, gives the leading instability since it corresponds to the largest superconducting critical temperature and the symmetry of the gap is given by the corresponding eigenvector.…”

“…A few studies also addressed the coexistence of superconductivity and longrange AF order but treated the pairing phenomenologically, and also found a d x 2 −y 2 -wave solution. 1,17,18 For hole-doped cuprates, stronger interactions imply that application of a weak-coupling approach to pairing is somewhat less justified. In addition, calculations of the spin wave spectrum suggest that the commensurate (π, π) order in this case is not the ground state solution, 19,20 complicating the theoretical modelling.…”

Spectroscopy of the neutron-rich hypernucleusHeΛ7from electron scattering

“…Although many species of Λ hypernuclei with masses A ≤ 209 have been observed [1,2], more systematic and precise data are still needed for further insight into the ΛN interaction. Nowadays, experimental studies of Λ hypernuclei use: (1) hadron beams at the Japan Proton Accelerator Research Complex (J-PARC) [3,4], (2) heavy ion beams at GSI [5][6][7], (3) heavy-ion colliders at the Brookhaven National Laboratory Relativistic Heavy Ion Collider [8] and the CERN Large Hadron Collider [9], and (4) electron beams at the Mainz Microtron [10,11] and the Thomas Jefferson National Accelerator Facility (JLab) [12][13][14][15][16][17][18][19][20][21]. The different production mechanisms are complementary and allow us to use their specific sensitivities to excite particular structures which highlight nuclear features of interest.…”

Experimental techniques and performance of Λ-hypernuclear spectroscopy with the (e,e′Gogami1, Chen2, Fujii3 et al. 2018Nuclear Instruments and Methods in Physics Research Section A: Self Cite12060View full textAdd to dashboardCite

“…Therefore, we attempted to optimize the angular acceptance of HES, taking into account the S/N and yield of Λ hypernuclei. For the purpose, we adopted the "tilt method", which was developed and proven to work sufficiently in the previous (e, e ′ K + ) experiment (JLab E01-011) [47,48]. The tilt method is a method of angular acceptance optimization in which the magnetic spectrometer is tilted vertically, as shown in Fig.…”

“…9) was evaluated by the Monte Carlo simulation, and was found to be Γ int = (5.67 ± 0.04) × 10 −5 (/electron) for a momentum range of p e ′ = 0.80-0.98 GeV/c. Table IV shows typical values of beam intensity I b , luminosity L, typical angle for scattered electrons θ e ′ , integrated virtual photon flux Γ int , solid-angle acceptance at the central K + momentum dΩ K , total detection efficiency ǫ tot , counting rates in e ′ spectrometer R e ′ , signal yield per hour per 100 nb/sr, S/N for the groundstate doublet peak of 12 Λ B at the peak position, comparing between E89-009 (without tilt method) [47,48,62] and E05-115 (with tilt method) [16,46]. Because of the tilt method, we were able to increase the luminosity by a factor of 230, while reducing the counting rate in the scattered electron spectrometer by a factor of 1/100.…”