We have exposed a dual-phase liquid argon time projection chamber (LAr-TPC) to a low energy pulsed narrow-band neutron beam, produced at the Notre Dame Institute for Structure and Nuclear ...Astrophysics, to study the scintillation light yield of recoiling nuclei. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the LAr-TPC and to select the energy of the recoiling nuclei. We report the observation of a significant dependence (up to 32%) on the drift field of liquid argon scintillation from nuclear recoils of energies between 10.8 and 49.9 keV. The field dependence is stronger at lower energies. Since it is the first measurement of such an effect in liquid argon, this observation is important because, to date, estimates of the sensitivity of LAr-TPC dark matter searches are based on the assumption that the electric field has only a small effect on the light yield from nuclear recoils.
We present the first measurement of the angular distribution for the exclusive process p¯p→ψ(2S)→e+e− based on a sample of 6844 events collected by the Fermilab E835 experiment. We find that the ...angular distribution is well described by the expected functional form dNdcosθ∗∝1+λcos2θ∗, where θ∗ is the angle between the antiproton and the electron in the center of mass frame, with λ=0.67±0.15(stat)±0.04(sys). The measured value for λ implies a small but non-zero ψ(2S) helicity 0 formation amplitude in p¯p, comparable to what is observed in J/ψ decays to baryon pairs.
A regenerable filter for liquid argon purification Curioni, A.; Fleming, B.T.; Jaskierny, W. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2009, Letnik:
605, Številka:
3
Journal Article
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Odprti dostop
A filter system for removing electronegative impurities from liquid argon is described. The active components of the filter are adsorbing molecular sieve and activated-copper-coated alumina granules. ...The system is capable of purifying liquid argon to an oxygen-equivalent impurity concentration of better than 30 parts per trillion, corresponding to an electron drift lifetime of at least 10
ms. Reduction reactions that occur at
∼
250
∘
C
allow the filter material to be regenerated in situ through a simple procedure. In the following work we describe the filter design, performance, and regeneration process.
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