The sPHENIX Micromegas Outer Tracker Aune, S.; Azmoun, B.; Bonenfant, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
September 2024, Letnik:
1066
Journal Article
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The sPHENIX Time Projection Chamber Outer Tracker (TPOT) is a Micromegas based detector. It is a part of the sPHENIX experiment that aims to facilitate the calibration of the Time Projection Chamber, ...in particular the correction of the time-averaged and beam-induced distortions of the electron drift. This paper describes the detector mission, setup, construction, installation, commissioning and performance during the first year of sPHENIX data taking.
P-type point contact (PPC) HPGe detectors are a leading technology for rare event searches due to their excellent energy resolution, low thresholds, and multi-site event rejection capabilities. We ...have characterized a PPC detector’s response to
α
particles incident on the sensitive passivated and p
+
surfaces, a previously poorly-understood source of background. The detector studied is identical to those in the
Majorana
Demonstrator
experiment, a search for neutrinoless double-beta decay (
0
ν
β
β
) in
76
Ge.
α
decays on most of the passivated surface exhibit significant energy loss due to charge trapping, with waveforms exhibiting a delayed charge recovery (DCR) signature caused by the slow collection of a fraction of the trapped charge. The DCR is found to be complementary to existing methods of
α
identification, reliably identifying
α
background events on the passivated surface of the detector. We demonstrate effective rejection of all surface
α
events (to within statistical uncertainty) with a loss of only 0.2% of bulk events by combining the DCR discriminator with previously-used methods. The DCR discriminator has been used to reduce the background rate in the
0
ν
β
β
region of interest window by an order of magnitude in the
Majorana
Demonstrator
and will be used in the upcoming LEGEND-200 experiment.
Abstract P-type point contact (PPC) HPGe detectors are a leading technology for rare event searches due to their excellent energy resolution, low thresholds, and multi-site event rejection ...capabilities. We have characterized a PPC detector’s response to $$\alpha $$ α particles incident on the sensitive passivated and p $$^+$$ + surfaces, a previously poorly-understood source of background. The detector studied is identical to those in the Majorana Demonstrator experiment, a search for neutrinoless double-beta decay ( $$0\nu \beta \beta $$ 0 ν β β ) in $$^{76}$$ 76 Ge. $$\alpha $$ α decays on most of the passivated surface exhibit significant energy loss due to charge trapping, with waveforms exhibiting a delayed charge recovery (DCR) signature caused by the slow collection of a fraction of the trapped charge. The DCR is found to be complementary to existing methods of $$\alpha $$ α identification, reliably identifying $$\alpha $$ α background events on the passivated surface of the detector. We demonstrate effective rejection of all surface $$\alpha $$ α events (to within statistical uncertainty) with a loss of only 0.2% of bulk events by combining the DCR discriminator with previously-used methods. The DCR discriminator has been used to reduce the background rate in the $$0\nu \beta \beta $$ 0 ν β β region of interest window by an order of magnitude in the Majorana Demonstrator and will be used in the upcoming LEGEND-200 experiment.
P-type point contact (PPC) HPGe detectors are a leading technology for rare event searches due to their excellent energy resolution, low thresholds, and multi-site event rejection capabilities. We ...have characterized a PPC detector’s response to
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\begin{document}$$\alpha $$\end{document}
α
particles incident on the sensitive passivated and p
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+
surfaces, a previously poorly-understood source of background. The detector studied is identical to those in the
Majorana
Demonstrator
experiment, a search for neutrinoless double-beta decay (
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\begin{document}$$0\nu \beta \beta $$\end{document}
0
ν
β
β
) in
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\begin{document}$$^{76}$$\end{document}
76
Ge.
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\begin{document}$$\alpha $$\end{document}
α
decays on most of the passivated surface exhibit significant energy loss due to charge trapping, with waveforms exhibiting a delayed charge recovery (DCR) signature caused by the slow collection of a fraction of the trapped charge. The DCR is found to be complementary to existing methods of
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\begin{document}$$\alpha $$\end{document}
α
identification, reliably identifying
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\begin{document}$$\alpha $$\end{document}
α
background events on the passivated surface of the detector. We demonstrate effective rejection of all surface
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\begin{document}$$\alpha $$\end{document}
α
events (to within statistical uncertainty) with a loss of only 0.2% of bulk events by combining the DCR discriminator with previously-used methods. The DCR discriminator has been used to reduce the background rate in the
\documentclass12pt{minimal}
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\usepackage{wasysym}
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\begin{document}$$0\nu \beta \beta $$\end{document}
0
ν
β
β
region of interest window by an order of magnitude in the
Majorana
Demonstrator
and will be used in the upcoming LEGEND-200 experiment.
The Majorana Demonstrator is a neutrinoless double-beta decay search consisting of a low-background modular array of high-purity germanium detectors, \(\sim2/3\) of which are enriched to 88\% in ...\(^{76}\)Ge. The experiment is also searching for double-beta decay of \(^{76}\)Ge to excited states (e.s.) in \(^{76}\)Se. \(^{76}\)Ge can decay into three daughter states of \(^{76}\)Se, with clear event signatures consisting of a \(\beta\beta\)-decay followed by the prompt emission of one or two \(\gamma\)-rays. This results with high probability in multi-detector coincidences. The granularity of the Demonstrator detector array enables powerful discrimination of this event signature from backgrounds. Using 41.9~kg-y of isotopic exposure, the Demonstrator has set world leading limits for each e.s.\ decay of \(^{76}\)Ge, with 90\% CL lower half-life limits in the range of \((0.75-4.0)\times10^{24}\)~y. In particular, for the \(2\nu\) transition to the first \(0^+\) e.s.\ of \(^{76}\)Se, a lower half-life limit of \(7.5\times10^{23}\)~y at 90\% CL was achieved.
P-type point contact (PPC) HPGe detectors are a leading technology for rare
event searches due to their excellent energy resolution, low thresholds, and
multi-site event rejection capabilities. We ...have characterized a PPC detector's
response to $\alpha$ particles incident on the sensitive passivated and p+
surfaces, a previously poorly-understood source of background. The detector
studied is identical to those in the MAJORANA DEMONSTRATOR experiment, a search
for neutrinoless double-beta decay ($0\nu\beta\beta$) in $^{76}$Ge. $\alpha$
decays on most of the passivated surface exhibit significant energy loss due to
charge trapping, with waveforms exhibiting a delayed charge recovery (DCR)
signature caused by the slow collection of a fraction of the trapped charge.
The DCR is found to be complementary to existing methods of $\alpha$
identification, reliably identifying $\alpha$ background events on the
passivated surface of the detector. We demonstrate effective rejection of all
surface $\alpha$ events (to within statistical uncertainty) with a loss of only
0.2% of bulk events by combining the DCR discriminator with previously-used
methods. The DCR discriminator has been used to reduce the background rate in
the $0\nu\beta\beta$ region of interest window by an order of magnitude in the
MAJORANA DEMONSTRATOR, and will be used in the upcoming LEGEND-200 experiment.
P-type point contact (PPC) HPGe detectors are a leading technology for rare event searches due to their excellent energy resolution, low thresholds, and multi-site event rejection capabilities. We ...have characterized a PPC detector's response to \(\alpha\) particles incident on the sensitive passivated and p+ surfaces, a previously poorly-understood source of background. The detector studied is identical to those in the MAJORANA DEMONSTRATOR experiment, a search for neutrinoless double-beta decay (\(0\nu\beta\beta\)) in \(^{76}\)Ge. \(\alpha\) decays on most of the passivated surface exhibit significant energy loss due to charge trapping, with waveforms exhibiting a delayed charge recovery (DCR) signature caused by the slow collection of a fraction of the trapped charge. The DCR is found to be complementary to existing methods of \(\alpha\) identification, reliably identifying \(\alpha\) background events on the passivated surface of the detector. We demonstrate effective rejection of all surface \(\alpha\) events (to within statistical uncertainty) with a loss of only 0.2% of bulk events by combining the DCR discriminator with previously-used methods. The DCR discriminator has been used to reduce the background rate in the \(0\nu\beta\beta\) region of interest window by an order of magnitude in the MAJORANA DEMONSTRATOR, and will be used in the upcoming LEGEND-200 experiment.
The sPHENIX Time Projection Chamber Outer Tracker (TPOT) is a Micromegas based detector. It is a part of the sPHENIX experiment that aims to facilitate the calibration of the Time Projection Chamber, ...in particular the correction of the time-averaged and beam-induced distortions of the electron drift. This paper describes the detector mission, setup, construction, installation, commissioning and performance during the first year of sPHENIX data taking.
The MAJORANA DEMONSTRATOR comprises two arrays of high-purity germanium detectors constructed to search for neutrinoless double-beta decay in 76-Ge and other physics beyond the Standard Model. Its ...readout electronics were designed to have low electronic noise, and radioactive backgrounds were minimized by using low-mass components and low-radioactivity materials near the detectors. This paper provides a description of all components of the MAJORANA DEMONSTRATOR readout electronics, spanning the front-end electronics and internal cabling, back-end electronics, digitizer, and power supplies, along with the grounding scheme. The spectroscopic performance achieved with these readout electronics is also demonstrated.
The MAJORANA DEMONSTRATOR is sensitive to rare events near its energy threshold, including bosonic dark matter, solar axions, and lightly ionizing particles. In this analysis, a novel training set of ...low energy small-angle Compton scatter events is used to determine the efficiency of pulse shape analysis cuts, and we present updated bosonic dark matter and solar axion results from an 11.17 kg-y dataset using a 5 keV analysis threshold.
