1 / 45

V.L. Dadykin and O. G. Ryazhskaya

Search for neutrino bursts from collapsing stars and Sensitivity of experiments for the different types of neutrinos. V.L. Dadykin and O. G. Ryazhskaya. How we see the present problems of the experiment related to the search for neutrino radiation from the collapsing star?

ebony
Download Presentation

V.L. Dadykin and O. G. Ryazhskaya

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Search for neutrino burstsfrom collapsing stars andSensitivity of experiments for the different types of neutrinos V.L. Dadykin and O. G. Ryazhskaya

  2. How we see the present problems of the experiment related to the search for neutrino radiation from the collapsing star? The study of the last stage of the massive main sequence stars evolution, when - the thermonuclear reserves were exhausted, - the macroscopic objects acquire nuclear density, - the conditions for gravitational collapse and the formation of neutron stars and black holes are created, - the gravitation governs the process has the story of several years. On April 1, 2011 we could celebrate 70 years of the publication of the paper of G. Gamov and M. Schoenberg (Phys. Rev., 1941, 59, 539), where the role of neutrino in the vast stellar catastrophes was discussed first time.

  3. H D He C O Fe Stable state: The forces of hot gas pressure compensate the gravitational ones. The temperature of the hot gas is supported by the nuclear radiation.Fn=Fg Fn Fg In the beginning of its evolution the star consists mainly of hydrogen. During the time due to the nuclear synthesis reaction the energy which keeps the star in equilibrium is released. After the production of Fe nuclei, the further evolution requires the energy consumption. The forming of Fe nuclei takes place in the coreFn<Fg. The star starts to compress, to collapse. Fe - nuclei are destroyed, electrons are practically pressed in the atomic nuclei under the action of gravitational forces. The electron neutrinos are emitted. Total energy v10% Mstar с2 - 10 % energy of star core mass

  4. URCA-process The idea was born in Rio casino “Urca” where it was possible to lose a lot of money very quickly. 1941«We have developed the general views regarding the role of neutrino emission in the vast stellar catastrophes known to astronomy, while the neutrinos are still considered as highly hypothetical particles because of the failure of all efforts made to detect them». G.Gamov, M.Schoenberg 1965Ya. B. Zel’dovich and O. H. Guseinov show, that gravitational collapse is accompanied by powerful and short (~10 ms) pulse of neutrino radiation. The neutronization process e 1965 The first proposal to search for collapsing starts (c.s.) using neutrino detectors by G. V. Domogatsky and G.T. Zatsepin 1965The birth of an experimental neutrino astrophysics.

  5. 1964-1966W. Fowler, F. Hoyle investigate the role of neutrinos in the last stages of stellar evolution. The dissociation of iron core plays an important role in stability loss by massive stellar envelopes. 1966The first calculation of collapse dynamics by S. Colgate, R.White 1966-1967The process of an implosion for stars with 32; 8; 4; or 2 solar masseshas been studied.The parameters of neutrino radiation are obtained (W. Arnett). 1967-1978The structure ofneutrino burst , e and eenergy spectra was studied by V.S.Imshennik, L.I.Ivanova, D.K.Nadyozhin, I.V.Otroshenko (Model I) at the first time . Also it was shown that the main flux of the neutrinos is emitted during the cooling stage of a new born neutron star. The duration of neutrino pulse was shown to be ~ 10 s. 1980-1982The time structure and energy spectra of e, e, ,  for the initial stage of collapse (<0.1 ms) are obtained by R.Bowers, J.Wilson (Model II). 1987 S. Bruenn’s calculations

  6. Neutrino detection from a collapsing star makes it possible • -To detect gravitational collapse even it is “silent” (isn’t accompanied by Supernova explosion); • -To investigate the dynamics of collapse; • -To estimate the temperature in the star center. If the star is nonmagnetic, nonrotating, spherically symmetrical the parameters of neutrino burst arethe following (Standard model): From the theory of the Standard collapse it follows that the total energy, carried out by all types of neutrinos,corresponds to ~ 0.1 of star core mass and is divided among these 6 components in equal parts.

  7. 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 electron antineutrino, have been used in searching for neutrino radiation, This choice is natural and connected with large anti e - 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. n + p  d + , E = 2.2 MeV The specific signature of event

  8. On February,23, 1987 A Supernova explosion in the Large Magellanic Cloud occured.

  9. February 23, 1987 1 3 5 7 9 11 optical observations mv=12m mv=6m Geograv 2:52:35,4 2:52:36,8 7:36:00 LSD 5 2 43,8 19 2:52:34 KII 2 7:35:35 11 (4) 44 47 7:35:41 IMB 8 47 7:36:06 BUST 2:52:34 1 6 21

  10. We see that the effects in the detectors are small and have poor statistics. This leads to quite understandable skepticism with regard to the significance of the effects themselves and the schemes for their interpretation. However, this experiment was unique up to now and therefore all the informationobtained at that time requires very careful treatment.

  11. The results are not explained in the frame of the standard collapse model, but can be naturally explained by rotating collapsar model (V.Imshennik,O. Ryazhskaya, Astron. Lett. 30, 14 (2004)) which predicts two-stage collapse. LSD detected neutrinofrom the stage of neutronization of the star due to the presence of theironin LSD. The first stage was ~ 5 hours early then second one.

  12. Fe (2 cm) 6 m 4.5 m 8m Fe (10 cm) Liquid Scintillator Detector (LSD) H=5200 m.w.e. 72 counters 90 tons ofСnH2n (n~9), 200 tons of Fe General view of LSD

  13. The rotation effects make it possible: 1. To resolve the problem of the transformation of collapse into an explosion for high-mass and collapsing supernovae (all types of SN, except the type Ia – thermonuclear SN) 2. To resolve the problem of two neutrino signals from SN 1987A, separated by a time interval of 4.7 h.

  14. Let us consider how the various detectors operated during the explosion of SN1987A could record the neutrino signals in terms of the model of a rotating collapsar, which reduces to the following: 1. Two neutrino bursts separated by a time tgrav~5 h must exist. 2. The neutrino flux during the first burst consists of electron neutrino with a total energyof 8.9х1052erg: the neutrino energy spectrum is hard and asymmetric with mean energies in the range of 25-50 MeV; the duration of the neutrino radiation is t ~ 2.4 - 6 s. 3. The second neutrino burst corresponds to the theory of standard collapse.

  15. Bugaev E.V., Bisnovaty-Kogan G.S. et al., 1979 The comparison of the total reduced cross-sections with νn cross-section on a free neutron for the reaction

  16. E=30 MeV (N1) E=40 MeV (N2) * De Rujula, 1987 ** Alexeyev, 1987

  17. Events 106 105 104 103 102 10 1 Energy range, detected by LSD Energy spectrum of the particles, coming from 2,8 cmiron plate (Geant4 calculations; histogram – total energy deposit) 0 5 10 15 20 25 30 35 40 Energy, MeV V. Boyarkin, 2004

  18. 2:52 UT results and 7:35 UT results correspond to a certain extent to the model of standard collapse (7:35 UT) Review by Imshennik V.S., Nadyozhin D.K. // Inter. J. Mod. Phys. A 20, 6597 (2005), the model of rotating collapsar (2:52 UT; 7:35 UT) Imshennik V.S., Space Sci Rev, 74, 325-334 (1995); Astronomy Lett., 34, 375 (2008); Imshennik V.S., Ryazhskaya O.G. // Astronomy Lett., 30, 14 (2004) However, a number of questions still remains!

  19. Timing diagram of the BUST pulses coincident with the LSD pulses within 1 s and similar coincidences for the К2 and LSD detectors as well as double pulses in LSD over the period from 0:00 to 10:00 UT on February 23, 1987.Nc (LSD-K2) = 8; Nc.by chance = 2Nc(LSD-BUST) = 13; Nc.by chance = 3Npairs by chance = 1,2 Coincidence by chance with SN 1/3000 years

  20. During last 40 years the following underground detectors were constructed by the Institute for Nuclear Research of the USSR: • АСД (Collapse) : INR RAS, Arteomovsk, 105 t of liquid scintillator, > 1 kt NaCl, 1977 • 2. BUST(INR RAS), 1978 • 3. LSD (INR RAS together with Institute of Cosmo Geophysics of CNR) Mt. Blanc, 90 t of scintillator and 200 t of iron, 1984 • 4. LVD (INR RAS and LNGS INFN, Gran Sasso) , • 0,35 кt scintillator and 0,33кt iron , 1992 • last version (1 kt of scintillator and 1 kt of iron), 2001 • One of main goals of the experiment is the search for neutrino burst from collapsing stars. • These detectors also are used for different studies in the field of underground physics. The possibility of a simultaneous detection of a neutrino burst by several detectors located in different places on the Earth strongly reduces noise and increases the reliability of results.

  21. g D=560cm e+ PM number=144 H=540cm ARTEOMOVSK Depth - 570±10 m.w.e. 105 t CnH2n+2 (n=10) =170s

  22. BAKSAN BAKSAN NEUTRINO OBSERVATORY Institute for Nuclear Research RAS

  23. LSD, Monte Bianco

  24. LVD – detector under Gran Sasso (LNGS) @ 3300 m.w.e. LVD • the largest iron-scintillation telescope in the world • 3 towers: • 840 scintillation counters (1010 tons of scintillator) • 1000 tons of iron • Study & important results in: • neutrino physics • astrophysics • cosmic ray physics • search for rare processes LVD is 10 times expanded version of the LSD (Mont Blanc) apparatus which has detected the ν-burst from SN 1987A at 2:52 UT on February, 23, 1987. LSD & LVD are Russian-Italian projects. Scintillator & scintillation counters were elaborated and produced in INR, Russia The main goal is to search for ν bursts from collapsing stars

  25. The search for different neutrino types from stellar collapses • LVD is possible to detect not only electron antineutrino via the inverse beta decay reaction but also electron neutrinos due to their interaction with iron and other types of neutrinos via interaction on carbon nuclei. • The criteria for off-line selection of neutrino events are developed. The experimental limit on the rate of Supernovae bursts without antineutrino emission is obtained for the first time. • Event selection • To search for different neutrino types from gravitational collapses the experimental data were analyzed. Two energy thresholds were taken: • The energy threshold in counter is 5 MeV. This allows not only to detect neutrino burst from a “standard” gravitational collapse due to inverse beta-decay reaction, but also to detect the cobalt and iron de-excitation gamma-quanta which is considered as electron neutrino detection sign. • The energy threshold in counter is 10 MeV. This allows to detect carbon de-excitation -quantum (15.1 MeV). In the absence of signal satisfying to the condition 1) this will be a sign of the  or  detection.

  26. Detectors are ready to search for neutrino radiation from the collapsing stars, but the nature is miserly for the presents. During 32 years [“Collapse” – 1977, LSD – 1984-2002, LVD – 1992(1 tower), 1998 (3 towers)] there were no observation of ν radiation from collapsing stars in the Galaxy. The collapse rate is less than 1 / 14 years at 90% c.l. During 10 years there were no observation of ν radiation from collapsing stars in the Galaxy without electron antineutrino radiation. The rate of the such collapses is less than 1 / 4 years at 90% c.l.

  27. We should be able: • to separate events appearing from neutrinos of different types; • to measure energy spectrum and time distribution of neutrinos; • to put new limits on the neutrino mass or to measure it; • to look for neutrino oscillations.

  28. Reactions for scintillation and Cherenkov counters

  29. * - E=40 MeV ** - E=30 MeV

  30. Baikal NEUTRINO DETECTORS Arteomovsk SNO LSD Baksan SOUD KamLAND SK LVD IMB Borexino KGF IceCube IceCube

  31. Ice Cube can be used efficiently to monitor our galaxy for supernova explosions. It is important, but in order to understand the processes having done in the collapsar it is necessary to have the detectors which can distinguish the neutrino types. The clear detection of antineutrino using the reaction p +  e+ + n can be obtain only in the case of double pulses measurements. It can be done by LVD, Borexino, KamLand, ASD. The number of events is less than in SK, but the signature of the events exists. All type of neutrino with energy higher than 15 MeV can be measured with ASD, BUST, LVD, Borexino, KamLand , due to the presence of C12 in scintillator. e for the moment can be detected only by ASD and LVD. First one, due to the presence of salt NaCl around it, second one due to the 900 t of Fe in its structure.

  32. LVD Modification Sodium chloride as a target for electron neutrino with energies ~50 MeV

  33. Why to use NaCl? • Standard collapse model (SCM): IBD • Non-standard: ε~70% in existing configuration [V.V. Boyarkin, O.G. Ryazhskaya // Proc. of 31st ICRC, Łódź, 2010]

  34. Adding NaCl to the detector structure: • increases neutron (IBD) detection efficiency up to ~20% • reduces the background (?) • and also increases the number of neutrino (non-SCM) interactions The work is in progress…

  35. g e+ ASDandLVD can detect all types of neutrinos Sodium Chloride as a target for Supernovae neutrinos V. Boyarkin, O. Ryazhskaya Proc. of 31st ICRC,Lodz 2009 and

  36. SNEWS SuperNova Early Warning System LVD SNO Alarm to scientific community BNL server IceCube SK

  37. Thanks!

  38. The name "SN" came from the observational astronomy data and deals with an instant appearance of a very bright star, with luminosity of about tens billions of the solar one.

  39. IAU Circ. 1987, N 4316; IAU Circ. 1987, N 4323 • Aglietta M., et al. // Europhys. Lett. , 1987, 3, p. 1315; • Дадыкин В.Л. и др. // Письма Астрон. ж. , 1988, 14, с. 107 • ДадыкинВ.Л., ЗацепинГ.Т., РяжскаяО.Г. // УФН, 1989, 158, с.140

  40. Kamiokande LSD Baksan (BUST) IMB

  41. g e+ Spherically symmetrical model LSD event is not similar to-detection Only 1 trigger has small pulse witht = 278 msec 1. 2 years of observations N (>5 pulses, deltaT <7s) = 0 2. Coincidence with SN < 1 per 1000 years 3. Distribution of pulses is uniform 4. Noises in the low energy channel (E>0.5 MeV) are absent 5. Counting rate of high energy pulses (E>25 MeV) is normal The LSD event is not due to fluctuations.

  42. The difference of neutrino emission in the standard model and in the model of rotating collapsar. Imshennik V.S., R.O.G., 2004 Tc~5x1012K Tc~5x1010K The main reaction:

  43. g e+ n n

More Related