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Piero GaleottiVulcano 2008 1 Search for neutrinos from collapsing stars in Italy (a 30 years report) C. Castagnoli, K. Lande, O. G. Ryazhskaya, O. Saavedra.

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Presentation on theme: "Piero GaleottiVulcano 2008 1 Search for neutrinos from collapsing stars in Italy (a 30 years report) C. Castagnoli, K. Lande, O. G. Ryazhskaya, O. Saavedra."— Presentation transcript:

1 Piero GaleottiVulcano 2008 1 Search for neutrinos from collapsing stars in Italy (a 30 years report) C. Castagnoli, K. Lande, O. G. Ryazhskaya, O. Saavedra G. T. Zatsepin …..and many others

2 Atmospheric Solar Sources CNBSupernova 2 Piero GaleottiVulcano 2008

3 3 Piero GaleottiVulcano 2008

4 Sun 4 Piero GaleottiVulcano 2008 1604 (Kepler) 1572 (Ticho) 1181 1054 (Crab) 1006

5 Phase of the collapse123 Total neutrino energy (10 53 erg) 0,11,73 Average neutrino energy (MeV) 121415 Time duration (s)0,043,115 1. Formation of the neutrino-sphere. 2. Accretion of the envelope on the core. 3. Kelvin cooling of the new-born neutron star. 5 Piero GaleottiVulcano 2008 Imshennik, Nadiozhin, Chechetkin, Ivanova, Domogatsky…

6 Piero GaleottiAstrofisica neutrinica6 Binding energy emitted as 99% Neutrinos of all flavors 1% Kinetic energy 0.01% Optical luminosity

7 7 Piero GaleottiVulcano 2008 Raffelt et al.

8 kT (MeV) E th (MeV)0,010,1 t (s) 110> 25 50,152,559,324,435,3 3 100,081,334,812,718,3 150,020,391,43,75,4 200,000,070,30,71,0 50,234,014,53855 4 100,173,010,92941 150,091,65,71522 200,040,62,25,98,5 50,315,3195173 5 100,274,616,74464 150,193,211,73145 200,111,86,61725 8 Piero GaleottiVulcano 2008

9 Neutrino 84, 11th Int. Conf.on Nutrino Physics and Astrophysics 562563

10 Main interactions in scintillator Inverse β decay: Neutrino-elettron scattering: Neutral currents interactions: Charged currents interactions: 10 Piero GaleottiVulcano 2008

11 Arteomovsk BST Soudan Kamioka Gran Sasso Homestake Mt Blanc Sudbury KGF The muon depth- intensity curve (underground data): curves are calculated by Bugaev et al., 1998

12 Liquid Scintillator Detector (LSD) Fe (2 cm) Fe (10 cm) H=5200 m.w.e. 72 counters 90 tons of С n H 2n (n~9), 200 tons of Fe 4.5 m 8m8m 6 m 12 Piero GaleottiVulcano 2008

13 How can the neutrino burst be identified ? T Detection of a burst of N pulses in a short time interval T А t 13 Piero GaleottiVulcano 2008

14 On line print of five pulses on 23 febbrury 1987 at 3 hr, 52 min, i.t., detected at Mt. Blanc LSD experiment Piero Galeotti 14 Vulcano 2008

15 15 Piero GaleottiVulcano 2008

16 +4 +6 +8 +10 +12 0 h 2 h 52 m 7 h 36 m 9 h 22 m 15 h 54 m Sk – 69 o 202 McNaught Radio (21cм) ? Shelton Jones DiscoveryJones Mont Blanc Kamioka, IMB, Baksan S W (У В) 1987А mvmvmvmv UT Shelton Feb24 Feb25 Piero Galeotti 16 Vulcano 2008

17 Mont Blanc 5 pulses E > 5 MeV UT 2:52:36.8 + 2 ms Kamioka11 8 7:35:35 + 1 min + (7 pulse at 7:54:22) ? IMB 8 25 7:35:41 + 5 ms BST (2+5) 10 2:52:34 and 7:36:06 (+ 2s-54s) DETECTED NEUTRINO SIGNALS The main signal comes from electron antineutrinos: e p ne + followed by e + e _ annihilation producing 2 s, detectable in scintillator but not in water. The Mont Blanc signal (5.8 < E vis < 7.8 MeV) corresponds to 4.6 < E vis < 6.6 MeV in water, at the limit to be detected in Kamioka. 17 Piero GaleottiVulcano 2008

18 Kamioka-LSD correlations 0 LSD t = 1.0 ms Kamioka t= 60 sec - 60 s + 60 s - 60 s + 60 s shift

19 LSD: 91 events, f=0.72/min E th 5-7MeV K-II: 191 events, f=1.4/min E th 7.5MeV (20 hits) T: from 1:45 to 3:45

20 LSD-KAMIOKANDE Coincidences in 34 hours- 17-2 hrs intervals – 11.45-22 Feb. – 21.45 - 23 Feb 11.45 17.45 23.45 5.45 11.45 17.45 2-22 2-23 TIME U.T 2 4 6 8 10 C t = 0.5 s Shift = 7.0 s Shift = 6.9 s 1462 events at LSD 2890 events at Kamioka Expected: 2.03

21 91 Mt. Blanc events 240 Baksan events

22

23 Annals New YORK Academy of Sciences, Vol. 571, pag. 577 New York 1989 Ed. by Ervin Fenyves

24

25 Coincidences Mt.Blanc-Kamioka Coincidence window t = + 0.5 s Bin width: 2 hours Coincidence time: 34 hours Kamioka time + 7 seconds N C = 1919120.5/7200 = 2.4 N O = 9 Mt. Blanc event time 1:45 – 3.45 U.T. 25 Piero GaleottiVulcano 2008

26 Piero Galeotti,26 Neutrino interactions in iron, Fe e + 56 Fe 56 Co+e - p

27 С n H 2n e e e 27 Piero GaleottiVulcano 2008

28 A rotating collapsar A rotating collapsar Imshennik Ryazhskaya Collapse Model View from above View from aside 5 h later 28 Piero GaleottiVulcano 2008

29 The LVD detector in Gran Sasso 840 scintillator counters, 1.5 m 3 each, are inserted in modules holding 8 counters each. The modules are grouped and stacked together to form three towers of 35 modules each. The scintillator of ach counter (1.2 tons) is watched from the top by 3 PMTs (15 cm diameter). 29 Piero GaleottiVulcano 2008

30 Topology INTERNAL Counters (M=570 tons) FRONT VIEW EXTERNAL Counters (M=430 tons) TOP VIEW 30 Piero GaleottiVulcano 2008

31 Neutrino Burst Detection in LVD interactions in scintillator e + p n + e + i ( x ) + e - i ( x ) + e - e + 12 C 12 N + e - e + 12 C 12 B + e + i ( x ) + 12 C i ( x ) + + 12 C NC and CC interactions on carbon nuclei useful for neutrino oscillation. e tagging through detection of delayed from n capture at low energy threshold, efficiency 60%. - Piero Galeotti 31 Vulcano 2008

32 LVD 10 years High duty cycle (>99.5% since 2002) Fiducial Active Mass (M~ 900 tons since Jun/2001) 32 Piero GaleottiVulcano 2008

33 Active Mass and Duty Cycle

34 The scintillator stability has been monitored for about 2 years using a 252 Cf n-source and periodically measuring: n-capture efficiency n mean capture time Both do not show any hint of variation or degradation. Other measurements are done on smaller samples by directly measuring transmittance and light yield. n-capture efficiency mean capture time stability survey Piero Galeotti 34 Vulcano 2008

35 RUNSince:To: Uptime [days] Duty Cycle Mass [tonn] PUBLISHED RUN 1Jun 6 th 92May 31 st 9328560%31023 rd ICRC 1993 RUN 2Aug 4 th 93Mar 11 th 9539774%39024 th ICRC 1995 RUN 3Mar 11 th 95Apr 30 th 9762790%40025 th ICRC 1997 RUN 4Apr 30 th 97Mar 15 th 9968594%41526 th ICRC 1999 RUN 5Mar 16 th 99Dec 11 th 0059295%58027 th ICRC 2001 RUN 6Dec 12 th 00Mar 24 th 0382198%84228 th ICRC 2003 RUN 7Mar 25 th 03Feb 4 th 05666>99%88129 th ICRC 2005 RUN 8Feb 5 th 05May 31 st 07846>99%93630 th ICRC 2007 LVD 4919 days rate of Galactic Gravitational Stellar Collapses [D20kpc]< 0.18 event/year 90% c.l. SUPER KAMIOKANDE rate of Galactic Gravitational Stellar Collapses [D100kpc] < 0.32 event/year 90% c.l. Galaxy survey Piero Galeotti 35 Vulcano 2008

36 Normalized to same number of events. In a 10 s burst, 10 events are expected from background. 36 Piero GaleottiVulcano 2008

37 37 Piero GaleottiVulcano 2008

38

39 The SNEWS Network SuperNova Early Warning System Give prompt information to astronomical community. Doing online coincidence, reduce to zero fake alarm. Triangulation possible LVDSK SNO BNLserver Every experiment looks for SN burst and send alarms at fixed rate (1/week); the network must be as much as possible fault tolerant. Alarm to scientific community 39 Piero GaleottiVulcano 2008


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