173 research outputs found
Parity violating electron scattering on the proton and deuteron at backward angles
The parity violating asymmetry in quasielastic electron scattering from the deuteron at backward scattering angles has been recently measured for the first time. Combined with the previously performed similar measurement on the proton, this measurement provides a determination of both the proton's strange magnetic form factor G^(a)_(M) and the axial vector e-N form factor G^(a)_(A). A preliminary analysis indicates that G^(a)_(M) is slightly positive but consistent with zero and that G^(e)_(A)(T=1) is in substantial disagreement with the theoretical estimate
Neutrino mass constraints on beta decay
Using the general connection between the upper limit on the neutrino mass and
the upper limits on certain types of non-Standard Model interaction that can
generate loop corrections to the neutrino mass, we derive constraints on some
non-Standard Model interactions. When cast into limits on
coupling constants, our results yield constraints on
scalar and tensor weak interactions improved by more than an order of magnitude
over the current experimental limits. When combined with the existing limits,
our results yield |C_S/C_V|\alt 5\times 10^{-3}, |C'_S/C_V|\alt 5\times
10^{-3}, |C_T/C_A| \alt 1.2\times 10^{-2} and |C'_T/C_A| \alt 1.2\times
10^{-2}.Comment: 4 pages, 3 figures; revised to reflect referee comments; accepted for
publication in Physical Review Letter
Optimization of the Ballistic Guide Design for the SNS FNPB 8.9 A Neutron Line
The optimization of the ballistic guide design for the SNS Fundamental
Neutron Physics Beamline 8.9 A line is described. With a careful tuning of the
shape of the curve for the tapered section and the width of the straight
section, this optimization resulted in more than 75% increase in the neutron
flux exiting the 33 m long guide over a straight m=3.5 guide with the same
length.Comment: 21 pages, 13 figures; added a paragraph on existing ballistic guides
to respond to referee comments; accepted for publication in Nuclear Inst. and
Methods in Physics Research,
Cavallo's Multiplier for in situ Generation of High Voltage
A classic electrostatic induction machine, Cavallo's multiplier, is suggested
for in situ production of very high voltage in cryogenic environments. The
device is suitable for generating a large electrostatic field under conditions
of very small load current. Operation of the Cavallo multiplier is analyzed,
with quantitative description in terms of mutual capacitances between
electrodes in the system. A demonstration apparatus was constructed, and
measured voltages are compared to predictions based on measured capacitances in
the system. The simplicity of the Cavallo multiplier makes it amenable to
electrostatic analysis using finite element software, and electrode shapes can
be optimized to take advantage of a high dielectric strength medium such as
liquid helium. A design study is presented for a Cavallo multiplier in a
large-scale, cryogenic experiment to measure the neutron electric dipole
moment.Comment: 9 pages, 10 figure
Recent Results from the SAMPLE Experiment
The previous two SAMPLE experiments yielded a measurement of the axial e-N form
factor G^e_A substantially different from the theoretical estimate. In order to confirm this observation,
a third SAMPLE experiment was carried out at a lower beam energy of 125 MeV (Q^2 = 0.038 (GeV/c)^2) on a deuterium target. The data analysis is now at the final stage and the results
are consistent with the theoretical prediction of the axial form factor G^e_A. Also, revaluation of the
background dilution factor and the electromagnetic radiative correction for the 200 MeV deuterium
data lead to updated results, which are also consistent with the theoretical prediction
Plans for a Neutron EDM Experiment at SNS
The electric dipole moment of the neutron, leptons, and atoms provide a
unique window to Physics Beyond the Standard Model. We are currently developing
a new neutron EDM experiment (the nEDM Experiment). This experiment, which will
be run at the 8.9 A Neutron Line at the Fundamental Neutron Physics Beamline
(FNPB) at the Spallation Neutron Source (SNS) at the Oak Ridge National
Laboratory, will search for the neutron EDM with a sensitivity two orders of
magnitude better than the present limit. In this paper, the motivation for the
experiment, the experimental method, and the present status of the experiment
are discussed.Comment: 9 Pages, 4 Figures, submitted to the proceedings of the Second
Meeting of the APS Topical Group on Hadronic Physics, Nashville, TN, October
22-24, 200
An alternative beadsâonâaâstring chromatin architecture in Thermococcus kodakarensis
We have applied chromatin sequencing technology to the euryarchaeon Thermococcus kodakarensis, which is known to possess histone-like proteins. We detect positioned chromatin particles of variable sizes associated with lengths of DNA differing as multiples of 30âbp (ranging from 30âbp to >450âbp) consistent with formation from dynamic polymers of the archaeal histone dimer. T. kodakarensis chromatin particles have distinctive underlying DNA sequence suggesting a genomic particle-positioning code and are excluded from gene-regulatory DNA suggesting a functional organization. Beads-on-a-string chromatin is therefore conserved between eukaryotes and archaea but can derive from deployment of histone-fold proteins in a variety of multimeric forms
Successful treatment of mucosa-associated lymphoid tissue lymphoma in a patient with gastric and rectal lesions with metachronous and ectopic development
A 75-year-old female, who had an abnormal stomach x-ray finding, was admitted to the hospital for further examination and therapy. Upper GI endoscopy showed reddish and swollen folds on the greater curvature of the gastric body and a biopsy was of this lesion revealed malignant lymphoma (small cell type or mucosa-associated lymphoid tissue (MALT) lymphoma suspected). The patient was infected with Helicobacter pylori (H. pylori), however, in response to the patient's wishes, a total gastrectomy, omentectomy and splenectomy were performed and the histological diagnosis was gastric MALT lymphoma. Two courses of CHOP therapy (cyclophosphamide (CPM) 750 mg/m2/day, day 1, adriamycin (ADM) 50 mg/m2/day, day 1, vincristine sulfate (VCR) 1.4 mg/m2/day, day 1, prednisolone 100 mg/body, day 1â5) were administered as adjuvant chemotherapy. A colonoscopic examination performed about 4.5 yr after the operation revealed rectal submucosal tumors and the biopsied specimens were diagnosed as malignant lymphoma. A transanal focal resection was performed and the histological diagnosis was metachronous and ectopic development of MALT lymphoma. The histological finding was similar to the gastric lesion. About 4 and 7 yr after the first development of rectal MALT lymphoma, MALT lymphomas developed repeatedly in the rectal lesion, however, these were resected repeatedly and no developmenthas occurred during the past two years. This report presents a very rare case of metachronous and ectopic MALT lymphoma development in the gastric and rectal lesions
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