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Title: Measurement of the cosmogenic 11C background with the Borexino Counting Test Facility

Abstract

Within next year, two organic liquid scintillator detectors, Borexino and KamLAND, will start the measurement of the mono-energetic 7Be solar neutrino flux in real time. Besides this objective, both of them have the potential to detect neutrinos from the pep fusion reaction and the CNO cycle in the Sun.For this purpose, two conditions are required: an extremely low radioactive contamination level and the efficient identification of the 11C background, produced in reactions induced by the residual cosmic muon flux on 12C. In the process, a free neutron is almost always produced. 11C can be tagged on an event by event basis by looking at the three-fold coincidence with the parent muon track and the subsequent neutron capture on protons. We tested successfully this coincidence method with the Borexino Counting Test Facility. The results are reported here.Moreover, we discuss on the effective potential of Borexino and KamLAND in detecting pep+CNO neutrinos compared to SNO+, a detector specifically designed for measuring the pep+CNO {nu} flux and that will take data from 2009.

Authors:
 [1];  [2]
  1. University of Milano, via Celoria 16, I-20133 Milano, (Italy)
  2. (Italy)
Publication Date:
OSTI Identifier:
21055015
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 897; Journal Issue: 1; Conference: LRT 2006: Topical workshop on low radioactivity techniques, Aussois (France), 1-4 Oct 2006; Other Information: DOI: 10.1063/1.2722077; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; BERYLLIUM 7; CAPTURE; CARBON 11; CARBON 12; CNO CYCLE; COINCIDENCE METHODS; COSMIC MUONS; COSMIC NEUTRINOS; LIQUID SCINTILLATION DETECTORS; LIQUID SCINTILLATORS; NEUTRINO DETECTION; NEUTRON REACTIONS; NEUTRONS; PROTONS; SOLAR NEUTRINOS; TEST FACILITIES

Citation Formats

Franco, D., and INFN, via Celoria 16, I-20133 Milan. Measurement of the cosmogenic 11C background with the Borexino Counting Test Facility. United States: N. p., 2007. Web. doi:10.1063/1.2722077.
Franco, D., & INFN, via Celoria 16, I-20133 Milan. Measurement of the cosmogenic 11C background with the Borexino Counting Test Facility. United States. doi:10.1063/1.2722077.
Franco, D., and INFN, via Celoria 16, I-20133 Milan. Wed . "Measurement of the cosmogenic 11C background with the Borexino Counting Test Facility". United States. doi:10.1063/1.2722077.
@article{osti_21055015,
title = {Measurement of the cosmogenic 11C background with the Borexino Counting Test Facility},
author = {Franco, D. and INFN, via Celoria 16, I-20133 Milan},
abstractNote = {Within next year, two organic liquid scintillator detectors, Borexino and KamLAND, will start the measurement of the mono-energetic 7Be solar neutrino flux in real time. Besides this objective, both of them have the potential to detect neutrinos from the pep fusion reaction and the CNO cycle in the Sun.For this purpose, two conditions are required: an extremely low radioactive contamination level and the efficient identification of the 11C background, produced in reactions induced by the residual cosmic muon flux on 12C. In the process, a free neutron is almost always produced. 11C can be tagged on an event by event basis by looking at the three-fold coincidence with the parent muon track and the subsequent neutron capture on protons. We tested successfully this coincidence method with the Borexino Counting Test Facility. The results are reported here.Moreover, we discuss on the effective potential of Borexino and KamLAND in detecting pep+CNO neutrinos compared to SNO+, a detector specifically designed for measuring the pep+CNO {nu} flux and that will take data from 2009.},
doi = {10.1063/1.2722077},
journal = {AIP Conference Proceedings},
number = 1,
volume = 897,
place = {United States},
year = {Wed Mar 28 00:00:00 EDT 2007},
month = {Wed Mar 28 00:00:00 EDT 2007}
}
  • Borexino is an experiment for low-energy neutrino spectroscopy at the Gran Sasso underground laboratories. It is designed to measure the monoenergetic {sup 7}Be solar neutrino flux in real time, via neutrino-electron elastic scattering in an ultrapure organic liquid scintillator. Borexino has the potential to also detect neutrinos from the pep fusion process and the CNO cycle. For this measurement to be possible, radioactive contamination in the detector must be kept extremely low. Once sufficiently clean conditions are met, the main background source is {sup 11}C, produced in reactions induced by the residual cosmic muon flux on {sup 12}C. In themore » process, a free neutron is almost always produced. {sup 11}C can be tagged on an event-by-event basis by looking at the threefold coincidence with the parent muon track and the subsequent neutron capture on protons. This coincidence method has been implemented on the Borexino Counting Test Facility data. We report on the first event-by-event identification of in situ muon-induced {sup 11}C in a large underground scintillator detector. We measure a {sup 11}C production rate of 0.130 {+-} 0.026(stat) {+-} 0.014(syst) day{sup -1} ton{sup -1}, in agreement with predictions from both experimental studies performed with a muon beam on a scintillator target and ab initio estimations based on the {sup 11}C producing nuclear reactions.« less
  • The prototype of the Borexino solar neutrino experiment is a low counting rate detector located at the underground Gran Sasso Laboratory. The detector was designed and built to achieve ultra-purity in an organic liquid scintillator on a massive scale. A number of ancillary plants and screening facilities are needed to reach low background in the sub-MeV region. The detector and its screening facilities are briefly described in this paper.
  • The solar neutrino experiment Borexino, which is located in the Gran Sasso underground laboratories, is in a unique position to study muon-induced backgrounds in an organic liquid scintillator. In this study, a large sample of cosmic muons is identified and tracked by a muon veto detector external to the liquid scintillator, and by the specific light patterns observed when muons cross the scintillator volume. The yield of muon-induced neutrons is found to be Y{sub n} = (3.10±0.11)·10{sup −4} n/(μ·(g/cm{sup 2})). The distance profile between the parent muon track and the neutron capture point has the average value λ = (81.5±2.7)more » cm. Additionally the yields of a number of cosmogenic radioisotopes are measured for {sup 12}N, {sup 12}B, {sup 8}He, {sup 9}C, {sup 9}Li, {sup 8}B, {sup 6}He, {sup 8}Li, {sup 11}Be, {sup 10}C and {sup 11}C. All results are compared with Monte Carlo simulation predictions using the FLUKA and GEANT4 packages. General agreement between data and simulation is observed for the cosmogenic production yields with a few exceptions, the most prominent case being {sup 11}C yield for which both codes return about 50% lower values. The predicted μ-n distance profile and the neutron multiplicity distribution are found to be overall consistent with data.« less
  • The Low Background Facility (LBF) at the Lawrence Berkeley National Laboratory (LBNL) in Berkeley, California provides low background gamma spectroscopy services to end-users in two unique facilities: locally within a carefully-constructed, low background laboratory space; and a satellite underground station (600 m.w.e) in Oroville, CA. These facilities provide a variety of gamma spectroscopy services to low background experiments primarily in the form of passive material screening for primordial radioisotopes (U, Th, K) or common cosmogenic and anthropogenic products, as well as active screening via neutron activation analysis for specific applications. A general overview of the facilities, services, and capabilities willmore » be discussed. Recent activities will also be presented, including the recent installation of a 3π muon veto at the surface facility, cosmogenic activation studies of TeO{sub 2} for CUORE, and environmental monitoring of Fukushima fallout.« less