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V.V. Ashikhmin¹, K.V. Manukovskiy¹², O.G. Ryazhskaya¹, I.R. Shakiryanova¹, A.V. Udin¹² for LVD collaboration ¹ Institute for Nuclear Research RAS, Moscow ²Institute for Theoretical and Experimental Physics, Moscow.
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V.V. Ashikhmin¹, K.V. Manukovskiy¹², O.G. Ryazhskaya¹, I.R. Shakiryanova¹, A.V. Udin¹² for LVD collaboration ¹Institute for Nuclear Research RAS, Moscow ²Institute for Theoretical and Experimental Physics, Moscow XV Lomonosov Conference on Elementary Particle Physics, Moscow, August 18-24,2011 SUPERNOVA NEUTRINO TYPE IDENTIFICATION WITH ADDING SODIUM CHLORIDE IN LVD Speaker Irina Shakiryanova
Large Volume Detector The main goal of LVD detector is the search for neutrino bursts from gravitational stellar collapses in our Galaxy. It's very important to distinguish the supernova neutrino types. • 840 liquid scintillation counters • The detector consists of 3 towers • Every tower has 5 columns and 7 levels • Column includes 8 counters per level situated in iron portatanks XV Lomonosov Conference on Elementary Particle Physics, Moscow, August 18-24,2011
Why to use NaCl? Standard collapse model (SCM): IBD Non-standard: ε~70% in existing configuration It was shown that the addition of NaCl to the structure of iron-scintillation detector can significantly improve the neutrino type identification as well as increase active mass of existing detector [V.V. Boyarkin, O.G. Ryazhskaya // Proc. of 31st ICRC, Łódź, 2010] XV Lomonosov Conference on Elementary Particle Physics, Moscow, August 18-24,2011
Experimental Setup Thickness of saltlayer - 50 mm 252Cf source on the roof of the tank #1135, under salt layer; Trigger – γ-quanta, looking for pulses in portatanks # 113 (down) & 114 (up). 1145 252Cf source 1135 NaCl XV Lomonosov Conference on Elementary Particle Physics, Moscow, August 18-24,2011
Results (1): Energy Spectra from γ-quanta only neutron source; no salt XV Lomonosov Conference on Elementary Particle Physics, Moscow, August 18-24,2011
Results (1): Energy Spectra from γ-quanta 50 mm of salt XV Lomonosov Conference on Elementary Particle Physics, Moscow, August 18-24,2011
Results (2): Integral time spectra only neutron source; no salt 1135 1145 XV Lomonosov Conference on Elementary Particle Physics, Moscow, August 18-24,2011
Results (2): Integral time spectra 50 mm of salt 1135 1145 XV Lomonosov Conference on Elementary Particle Physics, Moscow, August 18-24,2011
Results (3): Time values (fit data) μsec One can see that the presence of salt reduces the time of neutron capture XV Lomonosov Conference on Elementary Particle Physics, Moscow, August 18-24,2011
Results (4): Detection efficiencies XV Lomonosov Conference on Elementary Particle Physics, Moscow, August 18-24,2011
Results (4-2): Detection efficiencies Increases neutron (IBD) detection efficiency up to ~ 14% for two portatanks, up to ~ 15% for portatank 113
Calculating neutron efficiencies Number of neutrons per one decay is ~ 3,7 Nsmallpulses / NCf decays for two portatanks with salt is 2,488 Nsmallpulses / NCf decays for two portatanks without salt is 2,178 εn salt =2,488/3,7/0,94=72% εnno salt =2,178/3,7/0,94=63% εn salt / εnno salt = 1,14 For portatank 113 εn salt ~ 80%, εn no salt ~ 69%
Conclusions The addition of NaCl to the LVD detector structure: increases neutron (IBD) detection efficiency up to ~ 27% for counter 1135, up to ~12% for two counter configuration, for portatank in whole up to ~14% and also increases the number of neutrino (non-SCM) interactions XV Lomonosov Conference on Elementary Particle Physics, Moscow, August 18-24,2011
Thank you! XV Lomonosov Conference on Elementary Particle Physics, Moscow, August 18-24,2011
