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تسجيل مستخدم جديدمراقبة التصاعد المتضاد للنيوترون النووي مع الذرة
Observation of Coherent Elastic Neutrino-Nucleus Scattering
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تم الكشف عن الانتشار المتضامن للنيوترينوز على الذرات بعد أربعون عاما، على الرغم من أن الطاقة المتوقعة لهذه العملية هي أكبر في المقارنة مع جميع الارتباطات الخاصة بالنيوترينوز الخاصة بالطاقات المنخفضة. يوفر هذا النوع من التفاعل الفرص الجديدة لدراسة خصائص النيوترينوز، ويؤدي إلى تصغير حجم الكشف، مع التطبيقات التكنولوجية المحتملة. ونحن نلاحظ هذه العملية بمستوى ثقة 6.7 سيجما، باستخدام مصدر نور منخفض الخلفية، الذي يحتوي على 14.6 كغم من مشعل CsI [Na] المعروض لانبعاثات النيوترينوز من مصدر النيوترينوز المطروح (SNS) في مختبر أوك ريدج الوطني. وتم اكتشاف العلامات المميزة في الطاقة والوقت، التي يتوقعها النموذج القياسي لهذه العملية، في ظروف عالية للإشارة إلى الخلفية. وتم تحديد قيود أفضل على التفاعلات النيوترينوز غير القياسية مع الكوارك من هذا البيانات الأولية.
The coherent elastic scattering of neutrinos off nuclei has eluded detection for four decades, even though its predicted cross-section is the largest by far of all low-energy neutrino couplings. This mode of interaction provides new opportunities to study neutrino properties, and leads to a miniaturization of detector size, with potential technological applications. We observe this process at a 6.7-sigma confidence level, using a low-background, 14.6-kg CsI[Na] scintillator exposed to the neutrino emissions from the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. Characteristic signatures in energy and time, predicted by the Standard Model for this process, are observed in high signal-to-background conditions. Improved constraints on non-standard neutrino interactions with quarks are derived from this initial dataset.
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The COHERENT collaboration measured coherent elastic neutrino-nucleus scattering (CEvNS) for the first time at the Spallation Neutron Source at Oak Ridge National Laboratory, using a CsI[Na] detector. Here we discuss the nature of the CEvNS process,
physics motivations, and experimental considerations for measuring CEvNS. We describe the CsI[Na] measurement, along with status and future of COHERENT.
This release includes data and information necessary to perform independent analyses of the COHERENT result presented in Akimov et al., arXiv:1708.01294 [nucl-ex]. Data is shared in a binned, text-based format, including both signal and background re
gions, so that counts and associated uncertainties can be quantitatively calculated for the purpose of separate analyses. This document describes the included information and its format, offering some guidance on use of the data. Accompanying code examples show basic interaction with the data using Python.
The prospects of extracting new physics signals in a coherent elastic neutrino-nucleus scattering (CE$ u$NS) process are limited by the precision with which the underlying nuclear structure physics, embedded in the weak nuclear form factor, is known.
We present microscopic nuclear structure physics calculations of charge and weak nuclear form factors and CE$ u$NS cross sections on $^{12}$C, $^{16}$O, $^{40}$Ar, $^{56}$Fe and $^{208}$Pb nuclei. We obtain the proton and neutron densities, and charge and weak form factors by solving Hartree-Fock equations with a Skyrme (SkE2) nuclear potential. We validate our approach by comparing $^{208}$Pb and $^{40}$Ar charge form factor predictions with elastic electron scattering data. In view of the worldwide interest in liquid-argon based neutrino and dark matter experiments, we pay special attention to the $^{40}$Ar nucleus and make predictions for the $^{40}$Ar weak form factor and the CE$ u$NS cross sections. Furthermore, we attempt to gauge the level of theoretical uncertainty pertaining to the description of the $^{40}$Ar form factor and CE$ u$NS cross sections by comparing relative differences between recent microscopic nuclear theory and widely-used phenomenological form factor predictions. Future precision measurements of CE$ u$NS will potentially help in constraining these nuclear structure details that will in turn improve prospects of extracting new physics.
We report the first measurement of coherent elastic neutrino-nucleus scattering (cevns) on argon using a liquid argon detector at the Oak Ridge National Laboratory Spallation Neutron Source. Two independent analyses prefer cevns over the background-o
nly null hypothesis with greater than $3sigma$ significance. The measured cross section, averaged over the incident neutrino flux, is (2.2 $pm$ 0.7) $times$10$^{-39}$ cm$^2$ -- consistent with the standard model prediction. The neutron-number dependence of this result, together with that from our previous measurement on CsI, confirms the existence of the cevns process and provides improved constraints on non-standard neutrino interactions.
Coherent elastic neutrino scattering on the 40Ar nucleus is computed with coupled-cluster theory based on nuclear Hamiltonians inspired by effective field theories of quantum chromodynamics. Our approach is validated by calculating the charge form fa
ctor and comparing it to data from electron scattering. We make predictions for the weak form factor, the neutron radius, and the neutron skin, and estimate systematic uncertainties. The neutron-skin thickness of 40Ar40 is consistent with results from density functional theory. Precision measurements from coherent elastic neutrino-nucleus scattering could potentially be used to extract these observables and help to constrain nuclear models.
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