Sealed drift tube cosmic ray veto counters

Ríos, Roger Raupp; Tatar, E.; Bacon, Jeffrey; Bowles, T. J.; Hill, R. E.; Green, J.A.; Hogan, G. E.; Ito, T. M.; Makela, M.; Morris, C. L.; Mortenson, R.; Pasukanics, F.E.; Ramsey, J.; Saunders, A.; Seestrom, S.J.; Sondheim, W. E.; Teasdale, W. A.; Saltus, M.; Back, H. O.; Cottrell, Chris; Holley, A. T.; Pattie, R. W.; Young, A. R.; Broussard, L. J.; Filippone, B. W.; Hickerson, K. P.; Liu, Julie C.; Mendenhall, M. P.; Plaster, B.; Mammei, R.; Pitt, M.; Vogelaar, R. B.; Martin, J. W.

doi:10.1016/j.nima.2010.12.098

Cited by 9 publications

(6 citation statements)

References 10 publications

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“…3, a 15-cm diameter, 25-mm thick plastic scintillator (the "backing veto") was located immediately behind each of the spectrometer scintillators. Second, a large-scale plastic scintillator and sealed drift tube veto counters [61] surrounded the electron spectrometer magnet.…”

Section: G Cosmic-ray Muon Veto Systemmentioning

confidence: 99%

Measurement of the neutronβ-asymmetry parameterA0with ultracold neutrons

et al. 2012

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We present a detailed report of a measurement of the neutron β-asymmetry parameter A0, the parity-violating angular correlation between the neutron spin and the decay electron momentum, performed with polarized ultracold neutrons (UCN). UCN were extracted from a pulsed spallation solid deuterium source and polarized via transport through a 7-T magnetic field. The polarized UCN were then transported through an adiabatic-fast-passage spin-flipper field region, prior to storage in a cylindrical decay volume situated within a 1-T 2 × 2π solenoidal spectrometer. The asymmetry was extracted from measurements of the decay electrons in multiwire proportional chamber and plastic scintillator detector packages located on both ends of the spectrometer.

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Section: G Cosmic-ray Muon Veto Systemmentioning

confidence: 99%

Measurement of the neutronβ-asymmetry parameterA0with ultracold neutrons

et al. 2012

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“…The electron detector packages consist of a multiwire proportional chamber (MWPC) [16] for position reconstruction and backscattering identification and a plastic scintillator for timing and energy reconstruction. We also detect background muons using a combination of plastic scintillator paddles and Ar/ethane drift tubes [17] and 15 cm diameter, 25 mm thick scintillators placed directly behind the electron detectors (the "backing veto"). A schematic of the experimental apparatus is presented in Fig.…”

Section: Introductionmentioning

confidence: 99%

New result for the neutron β -asymmetry parameter A0 from UCNA

Brown¹,

Dees²,

Adamek³

et al. 2018

Phys. Rev. C

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Background:The neutron β-decay asymmetry parameter A 0 defines the angular correlation between the spin of the neutron and the momentum of the emitted electron. Values for A 0 permit an extraction of the ratio of the weak axial-vector to vector coupling constants, λ ≡ g A /g V , which under assumption of the conserved vector current hypothesis (g V = 1) determines g A . Precise values for g A are important as a benchmark for lattice QCD calculations and as a test of the standard model. Purpose: The UCNA experiment, carried out at the Ultracold Neutron (UCN) source at the Los Alamos Neutron Science Center, was the first measurement of any neutron β-decay angular correlation performed with UCN. This article reports the most precise result for A 0 obtained to date from the UCNA experiment, as a result of higher statistics and reduced key systematic uncertainties, including from the neutron polarization and the characterization of the electron detector response. Methods: UCN produced via the downscattering of moderated spallation neutrons in a solid deuterium crystal were polarized via transport through a 7 T polarizing magnet and a spin flipper, which permitted selection of either spin state. The UCN were then contained within a 3-m long cylindrical decay volume, situated along the central axis of a superconducting 1 T solenoidal spectrometer. With the neutron spins then oriented parallel or anti-parallel to the solenoidal field, an asymmetry in the numbers of emitted decay electrons detected in two electron detector packages located on both ends of the spectrometer permitted an extraction of A 0 .

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“…Each MWPC has 6 μm Mylar windows at the front and back that separate the chamber gas (100 torr neopentane) from the spectrometer vacuum and PMT housing ( 100 torr N 2 ). Cosmic-ray muon backgrounds are identified by a combination of plastic scintillator veto paddles and sealed Ar/ethane drift tube assemblies [14] around the electron detectors.…”

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confidence: 99%

Precision measurement of the neutronβ-decay asymmetry

Mendenhall¹,

Pattie²,

Bagdasarova³

et al. 2013

Phys. Rev. C

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A new measurement of the neutron β-decay asymmetry A 0 has been carried out by the UCNA Collaboration using polarized ultracold neutrons (UCNs) from the solid deuterium UCN source at the Los Alamos Neutron Science Center. Improvements in the experiment have led to reductions in both statistical and systematic uncertainties leading to A 0 = −0.11954(55) stat (98) Precision measurements of neutron β decay are an essential ingredient in understanding the electro-weak interaction in the light quark sector. In particular the axial-vector weak coupling constant, g A , is an important input to understanding the spin and flavor structure of the nucleon [1,2] and is being actively studied in detailed lattice QCD calculations [3,4]. It also plays an important role in a variety of astrophysical processes, including solar fusion cross sections important for energy and neutrino production in the Sun [5].The angular distribution of emitted electrons from decays of a polarized neutron ensemble can be expressed as [6]where A(E) specifies the decay asymmetry for electron energy E, v ≡ βc is the electron velocity, P is the mean neutron polarization, and θ is the angle between the neutron spin and the electron momentum. can be expressed aswhere λ ≡ g A /g V is the ratio of the vector to axial-vector weak coupling constants. Combining g A with independent measurements of the Fermi coupling constant G F , the Cabibbo-Kobayashi-Maskawa matrix element V ud , and the neutron lifetime τ n allows a precision test of the consistency of measured neutron β-decay observables [7]. The ultracold neutron asymmetry (UCNA) experiment is the first experiment to use ultracold neutrons (UCNs) in a precision measurement of neutron decay correlations. Following the publication of our earlier results [7][8][9], the UCNA Collaboration implemented a number of experimental improvements that led to reductions in both statistical and systematic uncertainties. These improvements, described below, include enhanced UCN storage, improved electron energy reconstruction, and continuous monitoring of the magnetic field in the spectrometer. This refined treatment of the systematic corrections and uncertainties begins to address issues of consistency in the world data set for A 0 .The UCNA experiment ran in 2010 using the "thin window geometry D" as described in [7,9], and collected a total of 20.6 × 10 6 β-decay events after all cuts were applied. We used the UCN source [10] Copyright by the American Physical Society. Mendenhall, M. P. ; Pattie, R. W., Jr. ; Bagdasarova, Y. ; et al., Mar 25, 2013. "Precision measurement of the neutron beta-decay asymmetry," PHYSICAL REVIEW C 87(3): 032501.

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Sealed drift tube cosmic ray veto counters

Cited by 9 publications

References 10 publications

Measurement of the neutronβ-asymmetry parameterA0with ultracold neutrons

Measurement of the neutronβ-asymmetry parameterA0with ultracold neutrons

New result for the neutron β -asymmetry parameter A0 from UCNA

Precision measurement of the neutronβ-decay asymmetry

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