117854820
A study of the sensitivity of the H dibaryon search experiment E813 at BNL through (Sigma(-),p)(atom) to Lambda + n
115608139
Search of new physics via eta rare decays
55784411
Test of fundamental symmetries via the Primakoff effect
The three neutral pseudoscalar mesons, pi^0, eta and eta', represent one of the most interesting systems in strong interaction physics. A study of the electromagnetic properties of these mesons provides a sensitive probe of the symmetry structure of QCD at low energy. A comprehensive experimental program at Jefferson Laboratory (Jlab) is aimed at gathering high precision measurements on the two-photon decay widths and transition form factors at low Q^2 of pi^0, eta and eta' via the Primakoff effect. The completed experiments on the pi^0 radiative decay width at Jlab 6 GeV, and other planned measurements at Jlab 12 GeV will provide a rich laboratory to test the chiral anomaly and to study the origin and dynamics of chiral symmetry breaking at the confinement scale of QCD.
103266766
Binding energy of (Lambda)He-7 and test of charge symmetry breaking in the Lambda N interaction potential
The binding energy of 7ΛHe has been obtained for the first time with reaction spectroscopy using the (e, e'K+) reaction at Jefferson Lab's Hall C. A comparison among the binding energies of the A = 7 T = l iso-triplet hypernuclei, 7ΛHe, 7ΛLi*and 7ΛBe, is made and possible charge symmetry breaking (CSB) in the ΛN potential is discussed. For 7ΛHe and 7ΛBe, the shifts in binding energies are opposite to those predicted by a recent cluster model calculation, which assumes that the unexplained part of the binding energy difference between 4ΛH and 4ΛHe, is due to the CSB of the ΛN potential. Further examination of CSB in light hypernuclear systems is required both experimentally and theoretically.
121399962
Time-zero fission-fragment detector based on low-pressure multiwire proportional chambers
Abstract A time-zero fission fragment (FF) detector, based on the technique of low-pressure multiwire proportional chambers (LPMWPC), has been designed and constructed for the heavy hypernuclear lifetime experiment (E95-002) at Thomas Jefferson National Accelerator Facility. Its characteristics and the method of time-zero reconstruction were investigated using fission fragments from a 252 Cf spontaneous fission source. The influence of the ionization energy loss was also studied. It is shown that Heptane, Hexane, and Isobutane gases at a pressure of 1–2 Torr are all suitable for such a FF detector. As desired by experiment, a timing resolution of about 200 ps (FWHM) for a chamber size of 21×21 cm 2 was achieved.
117101551
Comments on "eta -> gamma gamma Decay Width via the Primakoff Cross Section"
In a recent article by Rodrigues et al. [1] eta photo-nuclear data taken by Browman et al. [2] in 1974 were refit as a means to extract the eta->gamma gamma decay width. The key assertion in the author's analysis is attributing backgrounds in the eta angular distribution to nuclear incoherent production only. We disagree with this assertion and question the validity of the fitting procedure utilized in [1]. A reanalysis of the Cornell Primakoff data requires a detailed understanding of the hadronic and accidental backgrounds in the data, and the authors of [1] have not accomplished this task. [1] T. E. Rodrigues et al., Phys. Rev. Lett., 101, 012301 (2008). [2] A. Browman et al., Phys. Rev. Lett. 32, 1067 (1974).
119224046
The signature of an anisotropic distribution of gamma-ray bursts
Anomalies of the cosmic microwave background (CMB) maps have been widely acquainted nowadays from the Wilkinson Microwave Anisotropy Probe (WMAP) satellite to the Planck satellite. One of the anomalies is a multipole alignment from $l=2$ to $l=5$. In our work, we investigate the angular distribution of gamma-ray bursts (GRBs) to find whether there is the same anomaly of GRB as CMB. We perform spherical harmonics expansion on GRB samples to derive coefficients of a few first terms of the expansion terms and find that there is rough multipole alignment from $l=2$ to $l=4$ while the dipole and $l=5$ multipole is in a distant direction, and that the quadrupole is obviously planar and the other ones are normal.