High uniformity magnetic coil for search of neutron electric dipole moment Pérez Galván, A.; Plaster, B.; Boissevain, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2011, Letnik:
660, Številka:
1
Journal Article
Recenzirano
We present in this article a prototype magnetic coil that has been developed for a new search for the electric dipole moment of the neutron at the Spallation Neutron Source at Oak Ridge National ...Laboratory. The gradients of the magnetic field generated by the coil have been optimized to reduce known systematic effects and to yield long polarization lifetimes of the trapped particles sampling the highly uniform magnetic field. Measurements of the field uniformity of this prototype magnetic coil are also presented.
We present results from studies of the effectiveness of an overlap technique for forming a magnetic seal across a gap at the boundary between a cylindrical magnetic shield and an end-cap. In this ...technique a thin foil of magnetic material overlaps the two surfaces, thereby spanning the gap across the cylinder and the end-cap, with the magnetic seal then formed by clamping the thin magnetic foil to the surfaces of the cylindrical shield and the end-cap on both sides of the gap. In studies with a prototype 31-cm diameter, 91-cm long, 0.16-cm thick cylindrical magnetic shield and flared end-cap, the magnetic shielding performance of our overlap technique is comparable to that obtained with the conventional method in which the end-cap is placed in direct lapped contact with the cylindrical shield via through bolts or screws.
This paper describes the operation of the Coherent CAPTAIN-Mills (CCM) detector located at the Los Alamos Neutron Science Center at Los Alamos National Laboratory. CCM is a 10-ton liquid argon ...detector located 20 meters from a high flux neutron/neutrino source and is designed to search for sterile neutrinos (νs’s) and light dark matter (LDM). An engineering run was performed in fall 2019 to study the characteristics of the CCM120 detector by searching for coherent scattering signals consistent with νs’s and LDM resulting from the production and decays of π+ and π0 in the tungsten target. New parameter space in a leptophobic dark matter (DM) model was excluded for DM masses between ~2.0 and 30 MeV. The lessons learned from this run have guided the development and construction of the new CCM200 detector that will begin operations in 2021 and significantly improve on these searches.
We report the first measurement of an angular correlation parameter in neutron beta decay using polarized ultracold neutrons (UCN). We utilize UCN with energies below about 200 neV, which we guide ...and store for approximately 30 s in a Cu decay volume. The interaction of the neutron magnetic dipole moment with a static 7 T field external to the decay volume provides a 420 neV potential energy barrier to the spin state parallel to the field, polarizing the UCN before they pass through an adiabatic fast passage spin flipper and enter a decay volume, situated within a 1 T field in a 2x2pi solenoidal spectrometer. We determine a value for the beta-asymmetry parameter A_{0}=-0.1138+/-0.0046+/-0.0021.
PHENIX inner detectors Allen, M.; Bennett, M.J.; Bobrek, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2003, Letnik:
499, Številka:
2
Journal Article
Recenzirano
The timing, location and particle multiplicity of a PHENIX collision are determined by the Beam–Beam Counters (BBC), the Multiplicity/Vertex Detector (MVD) and the Zero-Degree Calorimeters (ZDC). The ...BBCs provide both the time of interaction and position of a collision from the flight time of prompt particles. The MVD provides a measure of event particle multiplicity, collision vertex position and fluctuations in charged particle distributions. The ZDCs provide information on the most grazing collisions. A Normalization Trigger Counter (NTC) is used to obtain absolute cross-section measurements for p–p collisions. The BBC, MVD and NTC are described below.
We report the first results of a search for leptophobic dark matter (DM) from the Coherent–CAPTAIN-Mills (CCM) liquid argon (LAr) detector. An engineering run with 120 photomultiplier tubes (PMTs) ...and 17.9 × 1020 protons on target (POT) was performed in fall 2019 to study the characteristics of the CCM detector. The operation of this 10-ton detector was strictly light based with a threshold of 50 keV and used coherent elastic scattering off argon nuclei to detect DM. Despite only 1.5 months of accumulated luminosity, contaminated LAr, and nonoptimized shielding, CCM’s first engineering run has already achieved sensitivity to previously unexplored parameter space of light dark matter models with a baryonic vector portal. With an expected background of 115 005 events, we observe 115 005 + 16.5 events which is compatible with background expectations. For a benchmark mediator-to-DM mass ratio of mVB=mχ = 2.1, DM masses within the range 9 MeV ≲ mχ ≲ 50 MeV are excluded at 90% C. L. in the leptophobic model after applying the Feldman-Cousins test statistic. CCM’s upgraded run with 200 PMTs, filtered LAr, improved shielding, and 10 times more POT will be able to exclude the remaining thermal relic density parameter space of this model, as well as probe new parameter space of other leptophobic DM models.
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