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Supernovae Explosion Detection vs Neutron Background on Example of Underground Detector

Supernovae Explosion Detection vs Neutron Background on Example of Underground Detector. LVD. Presenters: AGAFONOVA NATALIA BOYARKIN VADIM. Corno Grande. LVD H=3650 m.w.e. H min =3650 m.w.e. <E  >=280 GeV E  th = 2.2TeV at sea level.

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Supernovae Explosion Detection vs Neutron Background on Example of Underground Detector

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  1. Supernovae Explosion Detection vs Neutron Background on Example of Underground Detector LVD Presenters: AGAFONOVA NATALIA BOYARKIN VADIM

  2. Corno Grande

  3. LVD H=3650 m.w.e.

  4. Hmin=3650 m.w.e. <E>=280 GeV Eth = 2.2TeV at sea level -rate (1 tower)~ 120 h-1 Stopping muon rate (1 counter) 0.7510-3 • - trigger: ε 40 MeV, 2 sc Data taking trigger: th=4MeV (inner counters) th=7MeV (external counters) Event duration – 1 ms, th=0.6MeV (inner counter) E–resolution: ~30% =1-5MeV ~20%  5 MeV t–resolution: ~70 ns

  5. 1m 1,5m 1m L-shape tracking system Module – portatank, 8 sc

  6. The Tower

  7. The large volume detectors are the underground observatories for: • Neutrino astrophysics • Cosmic Rays physics • Search for point sources of cosmic rays • Study of neutrino oscillations • Search for rare events predicted by the theory (proton decay, monopoles, dark matter...) • - Geophysical phenomena

  8. General idea How can one detect the neutrino flux from collapsing stars? Until now, Cherenkov (H2O)andscintillation (СnH2n) detectors which are capable of detecting mainly , have been used in searching for neutrino radiation, This choice is natural and connected with large -p cross-section As was shown at the first time by G.T.Zatsepin, O.G.Ryazhskaya, A.E.Chudakov (1973), the proton can be used for a neutron capture with the following production of deuterium (d) with  - quantum emission with 180 – 200 µs. The specific signature of event

  9. А t T How can the neutrino burst be identified ? The detection of the burst of N impulses in short time interval T

  10. Reactions for scintillation and Cherenkov counters MeV cm2 MeV cm2 cm2 cm2

  11. Yu.V. Gaponov, S.V. Semenov e СnH2n 1+ GT __________10,589 1+ GT __________ 7,589 1+ GT __________ 4,589 0+ IAS __________ 3,589 1+ __________ 1,72 4+ __________ 0+ So one can expect 550 events from and more than 700 events from & in LVD

  12. The possibility to observe the neutrino burst depends on background conditions The source of background: • Cosmic rays 0<E< • а) muons • b) secondary particles generated by muons(e,,nand long-living isotopes) • с) the products of reactions of nuclear and electromagnetic interactions • 2. Natural radioactivity Е<30 MeV, mainly Е<2.65 MeV • а) , • b) n,(n ), U238, Th232 • c) , (n) d) Rn222 Background reduction: 1. Deep underground location 2. Using the low radioactivity materials 3. Anti-coincidence system 4. Using the reactions with good signature 5. The coincidence of signals in several detectors

  13. Tower Quarters 4Q

  14. C= 5 4 3 2 1 7 6 5 4 3 2 1 L 10.2 m 6.3 m 13.4 m 1 TOWER 280 scintillation counter (1.2 t/counter) 120 inner counters 3 TOWERS total 840 sc 1kt – scintillator 1kt – Fe

  15. neutrons nFe-capture nth p  (~7MeV) nth n  (2.2 MeV) np-capture p , ,

  16. single muon 72294 Neutrons= 5133.7 843.4 0-4 MeV 4-12 MeV

  17. muon bundles 23502 N=72294 Neutrons= 5949.6 908.2

  18. 0 - + n e+e-   hadronic and electromagnetic cascades 19603 Neutrons= 18537 2684

  19. For determining the specific neutron yield number we used the formula: the number of searched events the average muon path length total number of muon events both single muons and groups, and electromagnetic and hadronic cascades 6

  20. δ=0.07 4.3810-4 Per 1  (all processes) 7

  21. LVD En>0MeV 8

  22. q=(VFe+VPVC)/(VFe+VPVC+Vsc) q=0.160 V(M pvc=380kg) =0.86 m3 MFe =9.46t =7.8 g/cm3 Msc=9.2 t =0.78 g/cm3 K=240/146=1.644 sc = 0.9 Fe,Cl = 0.75

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