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Measurement of 40 Ar( n,p ) reaction and neutron capture on 40 Ar and 136 Xe

Measurement of 40 Ar( n,p ) reaction and neutron capture on 40 Ar and 136 Xe. Megha Bhike and Werner Tornow D uke U niversity and. T riangle U niversities N uclear L aboratory. TUNL and Duke Univ. AARM meeting, March 4 2013.

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Measurement of 40 Ar( n,p ) reaction and neutron capture on 40 Ar and 136 Xe

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  1. Measurement of 40Ar(n,p) reaction and neutron capture on 40Ar and 136Xe MeghaBhike and Werner Tornow Duke University and Triangle Universities Nuclear Laboratory TUNL and Duke Univ. AARM meeting, March 4 2013

  2. Motivation for the 40Ar(n,p), 40Ar(n,) and 136Xe(n,) Reaction Cross Section Measurements Standard  decay 0 decay If detected, 0 decay would indicate • The neutrino is its own antiparticle (Majorana Particle) • Lepton number violation, contrary to present formulation of standard model • An absolute scale of neutrino mass (from half-life) and nuclear matrix element TUNL and Duke Univ. AARM meeting, March 4 2013

  3. Motivation for the 40Ar(n,p), 40Ar(n,) and 136Xe(n,) Reaction Cross Section Measurements Argon is a favorite detection and shielding medium in: • 0 decay search-GERDA • dark-matter search-DEAP • Future Long Baseline Neutrino Experiment TUNL and Duke Univ. AARM meeting, March 4 2013

  4. Motivation for the 40Ar(n,p), 40Ar(n,) and 136Xe(n,) Reaction Cross Section Measurements 136Xe • Enriched Xenon Observatory (0 ) • KamLAND-Zen • (0 ) TUNL and Duke Univ. AARM meeting, March 4 2013

  5. Motivation for the 40Ar(n,p), 40Ar(n,) and 136Xe(n,) Reaction Cross Section Measurements Challenges in 0 Detection • Long 0 decay half-life leads to low statistics in decay spectrum • Muon-induced spallation neutrons can produce background signals indistinguishable from the signals of interest. • Need to measure neutron induced cross sections on 40Ar and 136Xe upto En = 20 MeV • 136Xe(n, )137Xe,  decay, T1/2 = 3.82 mins, • Energy resolution of EXO = 1.67 % • 2478.8 keV, 2463.3 keV,  -ray from 137Cs • Energy resolution of KamLAND = 4.2 % • 2422.7keV, 2463.3 keV, 2474.8 keV and 2490.4 keV TUNL and Duke Univ. AARM meeting, March 4 2013

  6. Status of the (n,) Measurements on 40Ar • (n,) data for 40Ar between 0.1 -1 MeV • Old measurements in low energy region • Wright Air Devel. Centre Reports, No.59, p.107 (1959) USA • No data above 1 MeV • Different evaluations Goal: To measure40Ar(n,)41Ar cross section from 0.7 to 14.8MeV within 5-10 % TUNL and Duke Univ. AARM meeting, March 4 2013

  7. Status of the (n,) Measurements on 136Xe • few measurements in thermal region • No data in the entire energy range from 0.7 to 14.8 MeV • Different evaluation Goal: To measure136Xe(n,)137Xe cross section from 0.7 to 14.8 MeV within 10-15 % TUNL and Duke Univ. AARM meeting, March 4 2013

  8. Activation Measurements at TUNL DENIS Neutron production Activation parameters Neutron TOF area • T(p,n), D(d,n) and T(d,n) neutron sources • Ip/d= 1 -2 mA • En = 0.7 – 14.8 MeV • Pulsed at 2.5 MHz • n = (1-5)x107 n/(cm2 sec) • High-purity Argon (natural)/Xenon (enriched) gas in high pressure stainless steel/ titanium sphere • 2 monitor foils (In & Au) • n-flux monitoring: BC -501A neutron monitor detector (00) TUNL and Duke Univ. AARM meeting, March 4 2013

  9. Activation Measurements at TUNL DENIS Experimental Setup High Res. Gamma Spec. • 4x60% HPGe detectors • Genie 2006 spec. system • Identical counting conditions C. Bhatia et al., PRC 86, 041602(R) 2012 TUNL and Duke Univ. AARM meeting, March 4 2013

  10. 41Ar g-Ray Signature • Measured 7000-8000 g-events after 2 hrs irradiation and 14 hrs counting time • Measured 10 energies in Nov 2012 – Feb 2013 runs TUNL and Duke Univ. AARM meeting, March 4 2013

  11. 137Xe 99.6(11)% 455.5 keV 5/2+; 455.5, T1/2< 0.1 ns 31.2(5)% 7/2+; 30.07 years 137Cs 137Xe g-Ray Signature • Measured 300-550 g-events after 15 mins irradiation and 25 minscounting time • Measured 11 energies in Nov 2012 – Feb 2013 runs TUNL and Duke Univ. AARM meeting, March 4 2013

  12. Monitor Reactions Measurement of the neutron fluence using a set of witness foils mounted before & after the 136Xe/40Ar targets 197Au(n,) T1/2 = 2.69 d, E = 411.8 keV 115In(n,n) T1/2 = 4.49 h, E =336.2 keV 197Au(n,2n) T1/2 = 6.17 d, E = 355.7 keV TUNL and Duke Univ. AARM meeting, March 4 2013

  13. Correction for parasitic neutrons TUNL and Duke Univ. AARM meeting, March 4 2013

  14. Experimental Results: 40Ar(n,)41Ar • Cross sections are of few mb level • TALYS – 2012 agrees well with TUNL data • Good agreement with data set of Bostrom et al. TUNL and Duke Univ. AARM meeting, March 4 2013

  15. Experimental Results: 40Ar(n,p) 40Cl • Fair agreement with the ENDF-VII.1 evaluation up to about 12.5 MeV and with G4NDL3.13 above • Good agreement with measurement by Gray et al., 1965. C. Bhatia et al., PRC 86, 041602(R) 2012 TUNL and Duke Univ. AARM meeting, March 4 2013

  16. Experimental Results: 136Xe(n,)137Xe • Cross sections are of mb level • TUNL data do not agree with both ENDF/B-VII.1 and TALYS-2012 evaluations TUNL and Duke Univ. AARM meeting, March 4 2013

  17. Future plans: 76Ge(n,)77Ge • no measurement from 0.7 to 14.8 MeV • Different evaluations •  transition at 2037.78 keV • Ge target of 86% 76Ge and 14% 74Ge • test run at 2 MeV last week taken from nndc TUNL and Duke Univ. AARM meeting, March 4 2013

  18. Summary • Complete cross section measurements of the 40Ar(n,p)40Cl reaction • Capture cross sections on 40Ar and 136Xe measured at 10 energies from 0.7 to 14.8 MeV. Plan to carry out measurements between 8 – 14 MeV • These measurements are important for estimating potential background events in the neutrinoless double-beta decay experiments, neutrino detectors in general and dark matter experiments AARM meeting, March 4 2013 TUNL and Duke Univ.

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