A measurement of the mean electronic excitation energy of liquid xenon. (arXiv:2109.07151v2 [physics.ins-det] UPDATED)
<a href="http://arxiv.org/find/physics/1/au:+Baudis_L/0/1/0/all/0/1">Laura Baudis</a>, <a href="http://arxiv.org/find/physics/1/au:+Sanchez_Lucas_P/0/1/0/all/0/1">Patricia Sanchez-Lucas</a>, <a href="http://arxiv.org/find/physics/1/au:+Thieme_K/0/1/0/all/0/1">Kevin Thieme</a>
Detectors using liquid xenon as target are widely deployed in rare event
searches. Conclusions on the interacting particle rely on a precise
reconstruction of the deposited energy which requires calibrations of the
energy scale of the detector by means of radioactive sources. However, a
microscopic calibration, i.e. the translation from the number of excitation
quanta into deposited energy, also necessitates good knowledge of the energy
required to produce single scintillation photons or ionisation electrons in
liquid xenon. The sum of these excitation quanta is directly proportional to
the deposited energy in the target. The proportionality constant is the mean
excitation energy and is commonly known as $W$-value. Here we present a
measurement of the $W$-value with electronic recoil interactions in a small
dual-phase xenon time projection chamber with a hybrid (photomultiplier tube
and silicon photomultipliers) photosensor configuration. Our result is based on
calibrations at $mathcal{O}(1-10 , mathrm{keV})$ with internal $^{37}$Ar and
$^{83text{m}}$Kr sources and single electron events. We obtain a value of
$W=11.5 , ^{+0.2}_{-0.3} , mathrm{(syst.)} , mathrm{eV}$, with negligible
statistical uncertainty, which is lower than previously measured at these
energies. If further confirmed, our result will be relevant for modelling the
absolute response of liquid xenon detectors to particle interactions.
Detectors using liquid xenon as target are widely deployed in rare event
searches. Conclusions on the interacting particle rely on a precise
reconstruction of the deposited energy which requires calibrations of the
energy scale of the detector by means of radioactive sources. However, a
microscopic calibration, i.e. the translation from the number of excitation
quanta into deposited energy, also necessitates good knowledge of the energy
required to produce single scintillation photons or ionisation electrons in
liquid xenon. The sum of these excitation quanta is directly proportional to
the deposited energy in the target. The proportionality constant is the mean
excitation energy and is commonly known as $W$-value. Here we present a
measurement of the $W$-value with electronic recoil interactions in a small
dual-phase xenon time projection chamber with a hybrid (photomultiplier tube
and silicon photomultipliers) photosensor configuration. Our result is based on
calibrations at $mathcal{O}(1-10 , mathrm{keV})$ with internal $^{37}$Ar and
$^{83text{m}}$Kr sources and single electron events. We obtain a value of
$W=11.5 , ^{+0.2}_{-0.3} , mathrm{(syst.)} , mathrm{eV}$, with negligible
statistical uncertainty, which is lower than previously measured at these
energies. If further confirmed, our result will be relevant for modelling the
absolute response of liquid xenon detectors to particle interactions.
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