IMB Detectors Research Articles

Exciting prospects for detecting late-time neutrinos from core-collapse supernovae

The importance of detecting neutrinos from a Milky Way core-collapse supernova is well known. An under-studied phase is proto-neutron star cooling. For SN 1987A, this seemingly began at about 2 s, and is thus probed by only 6 of the 19 events (and only the $\bar{\nu}_e$ flavor) in the Kamiokande-II and IMB detectors. With the higher statistics expected for present and near-future detectors, it should be possible to measure detailed neutrino signals out to very late times. We present the first comprehensive study of neutrino detection during the proto-neutron star cooling phase, considering a variety of outcomes, using all flavors, and employing detailed detector physics. For our nominal model, the event yields (at 10 kpc) after 10 s -- the approximate duration of the SN 1987A signal -- far exceed the entire SN 1987A yield, with $\simeq$250 $\bar{\nu}_e$ events (to 50 s) in Super-Kamiokande, $\simeq$110 $\nu_e$ events (to 40 s) in DUNE, and $\simeq$10 $\nu_\mu, \nu_\tau, \bar{\nu}_\mu, \bar{\nu}_\tau$ events (to 20 s) in JUNO. These data would allow unprecedented probes of the proto-neutron star, including the onset of neutrino transparency and hence its transition to a neutron star. If a black hole forms, even at very late times, this can be clearly identified. But will the detectors fulfill their potential for this perhaps once-ever opportunity for an all-flavor, high-statistics detection of a core collapse? Maybe. Further work is urgently needed, especially for DUNE to thoroughly investigate and improve its MeV capabilities.

Improved analysis of SN1987A antineutrino events

We propose a new parameterization of the antineutrino flux from core collapse supernovae, that allows an interpretation of its astrophysical parameters within the Bethe and Wilson scenario for the explosion, and that leads to a reasonable (smooth) behavior of the average energy and of the luminosity curve. We apply it to analyze the events observed by Kamiokande-II, IMB and Baksan detectors in correlation with SN1987A. For the first time, we consider in the same analysis all data characteristics: times, energies and angles of the observed events. We account for the presence of background and evaluate the impact of neutrino oscillations. The hypothesis that the initial luminous phase of emission (accretion) is absent can be rejected at the 2% significance level. Without the need to impose external priors in the likelihood analysis, the best-fit values of the astrophysical parameters are found to be in remarkable agreement with the expectations of the standard core collapse scenario; in particular, the electron antineutrino-sphere radius is 16 km, the duration of the accretion phase is found to be 0.55 s, and the initial accreting mass is 0.22 M ⊙ . Similarly, the total energy emitted in neutrinos is 2.2 × 10 53 erg , again close to the expectations. The errors on the parameters are evaluated and found to be relatively large, consistently with the limited number of detected events; the two-dimensional confidence regions, that demonstrate the main correlations between the parameters, are also given.

Direct measurement of supernova neutrino emission parameters with a gadolinium-enhanced Super-Kamiokande detector

The time-integrated luminosity and average energy of the neutrino emission spectrum are essential diagnostics of core-collapse supernovae. The SN 1987A electron antineutrino observations by the Kamiokande-II and IMB detectors are only roughly consistent with each other and theory. Using new measurements of the star formation rate history, we reinterpret the Super-Kamiokande upper bound on the electron antineutrino flux from all past supernovae as an excluded region in neutrino emission parameter space. A gadolinium-enhanced Super-Kamiokande should be able to jointly measure these parameters, and a future megaton-scale detector would enable precision studies.

PHYSICS OF SUPERNOVAE

The origin of cosmic rays (CR) is supposed to be closely connected with supernovae (SNe) which create the conditions favorable for various mechanisms of the CR acceleration to operate effectively. First, modern ideas about the physics of the SN explosion are briefly discussed: the explosive thermonuclear burning in degenerate white dwarfs resulting in Type Ia SNe and the gravitational collapse of stellar cores giving rise to other types of SNe (Ib, Ic, IIL, IIP). Next, we survey some global properties of the SNe of different types: the total explosion energy distribution of various components (kinetic energy of the hydrodynamic flow, electromagnetic radiation, temporal behavior of the neutrino emission and individual energies of different neutrino flavors). Then, we discuss in the possibility of direct hydrodynamic acceleration by the shock wave breakout and the properties of the SN shocks in the circumstellar medium. Then the properties of the neutrino radiation from the core-collapse SNe and a possibility to incorporate both the LSD Mont Blanc neutrino event and that recorded by the K II and IMB detectors into a single scenario are described in detail. Finally, the issues of the neutrino nucleosynthesis and of the connection between supernova and gamma-ray bursts are discussed.

SN1987A and the properties of the neutrino burst

We reanalyze the neutrino events from SN1987A in IMB and Kamiokande-II (KII) detectors, and compare them with the expectations from simple theoretical models of the neutrino emission. In both detectors the angular distributions are peaked in the forward direction, and the average cosines are 2 sigma above the expected values. Furthermore, the average energy in KII is low if compared with the expectations; but, as we show, the assumption that a few (probably one) events at KII have been caused by elastic scattering is not in contrast with the ``standard'' picture of the collapse and yields more satisfactory distributions in angle and (marginally) in energy. The observations give useful information on the astrophysical parameters of the collapse. We find that the mean energy of electron antineutrinos is $〈E〉=12--15\mathrm{MeV},$ the total energy radiated around $(2--5)\ifmmode\times\else\texttimes\fi{}{10}^{53}\mathrm{erg},$ and there is a hint for a relatively large radiation of nonelectronic neutrino species. These properties of the neutrino burst are not in disagreement with those suggested by the current theoretical paradigm, but the data leave wide space to nonstandard pictures, especially when neutrino oscillations are included.

Neutrinos from SN1987A: flavor conversion and interpretation of results

After recent results from solar neutrino experiments and KamLAND we can definitely say that neutrinos from SN1987A underwent flavor conversion, and the conversion effects must be taken into account in the analysis of the data. Assuming the normal mass hierarchy of neutrinos we calculate the permutation factors p for the Kamiokande-2, IMB and Baksan detectors. The conversion inside the star leads to p=0.28–0.32; the oscillations in the matter of the Earth give partial (and different for different detectors) regeneration of the original ν̄e signal, reducing this factor down to 0.15–0.20 (at E=40 MeV). We study in details the influence of conversion on the observed signal depending on the parameters of the original neutrino spectra. For a given set of these parameters, the conversion could lead to an increase of the average energy of the observed events up to 50% and of the number of events by a factor of 2 at Kamiokande-2 and by a factor of 3–5 at IMB. Inversely, we find that neglecting the conversion effects can lead up to 50% error in the determination of the average energy of the original ν̄e spectrum and about 50% error in the original luminosity. Comparing our calculations with experimental data we conclude that the Kamiokande-2 data alone do not favor strong conversion effect, which testifies for small difference of the original ν̄e and ν̄μ spectra. In contrast, the combined analysis of the Kamiokande and IMB results slightly favors strong conversion effects (that is, large difference of the original spectra). In comparison with the no-oscillation case, the latter requires lower average energy and higher luminosity of the original ν̄e flux.

Neutrinos from SN1987A, large mixings and Earth matter effects

We show that oscillation effects in the matter of the Earth can provide explanation of the difference in the energy spectra of the events detected by Kamiokande-2 and IMB detectors from SN1987A as well as the absence of high-energy events with E ≳ 40 MeV. This explanation requires the neutrino oscillation parameters Δ m 2 and sin 2 2θ to be in the region of the LMA solution of the solar neutrino problem.

Neutrinos from SN 1987A, Earth matter effects, and the large mixing angle solution of the solar neutrino problem

We study the properties of the oscillation effects in the matter of the Earth on antineutrino fluxes from supernovae. We show that these effects can provide an explanation of the difference in the energy spectra of the events detected by Kamiokande-2 and IMB detectors from SN 1987A as well as the absence of high-energy events with $E\ensuremath{\gtrsim}40$ MeV. This explanation requires the neutrino oscillation parameters $\ensuremath{\Delta}{m}^{2}$ and ${\mathrm{sin}}^{2}2\ensuremath{\theta}$ to be in the region of the large mixing angle solution of the solar neutrino problem and the normal mass hierarchy if $|{U}_{e3}{|}^{2}\ensuremath{\gtrsim}{10}^{\ensuremath{-}3}.$ The hierarchy can be inverted if $|{U}_{e3}{|}^{2}\ensuremath{\ll}{10}^{\ensuremath{-}3}.$ The solution of the solar neutrino problem based on ${\ensuremath{\nu}}_{e}$ conversion to a pure sterile state is disfavored by SN 1987A data.

Neutrino oscillations and the supernova 1987A signal.

We study the impact of neutrino oscillations on the interpretation of the supernova (SN) 1987A neutrino signal by means of a maximum-likelihood analysis. We focus on oscillations between $\overline\nu_e$ with $\overline\nu_\mu$ or $\overline\nu_\tau$ with those mixing parameters that would solve the solar neutrino problem. For the small-angle MSW solution ($\Delta m^2\approx10^{-5}\,\rm eV^2$, $\sin^22\Theta_0\approx0.007$), there are no significant oscillation effects on the Kelvin-Helmholtz cooling signal; we confirm previous best-fit values for the neutron-star binding energy and average spectral $\overline\nu_e$ temperature. There is only marginal overlap between the upper end of the 95.4\% CL inferred range of $\langle E_{\overline\nu_e}\rangle$ and the lower end of the range of theoretical predictions. Any admixture of the stiffer $\overline\nu_\mu$ spectrum by oscillations aggravates the conflict between experimentally inferred and theoretically predicted spectral properties. For mixing parameters in the neighborhood of the large-angle MSW solution ($\Delta m^2\approx10^{-5}\,\rm eV^2$, $\sin^22\Theta_0\approx0.7$) the oscillations in the SN are adiabatic, but one needs to include the regeneration effect in the Earth which causes the Kamiokande and IMB detectors to observe different $\overline\nu_e$ spectra. For the solar vacuum solution ($\Delta m^2\approx10^{-10}\,\rm eV^2$, $\sin^22\Theta_0\approx1$) the oscillations in the SN are nonadiabatic; vacuum oscillations take place between the SN and the detector. If either of the large-angle solutions were borne out by the upcoming round of solar neutrino experiments, one would have to conclude that the SN~1987A $\overline\nu_\mu$ and/or $\overline\nu_e$ spectra had been much softer than predicted by current

Calibration of the IMB detector

The IMB detector (named after its founding institutions: University of California, Irvine, the University of Michigan and Brookhaven National Laboratory) collected data on a wide range of phenomena for over eight years. It was the first and the largest of the ring imaging water Cherenkov detectors. The detector consisted of 8000 metric tons of ultra-pure water instrumented with 2048 photomultiplier tubes (PMTs). The PMTs were placed on the roof, floor, and walls of the detector in a lattice of approximately 1 m spacing. It made measurements of contained events that ranged in energy from 15 MeV up to 1.5 GeV. This paper describes the calibration of the IMB detector. This procedure was accurate and stable over a wide range of physical variables. It was used with little change throughout the entire eight-year lifetime of the experiment. The IMB calibration is a model for future large-scale detectors that employ the water Cherenkov technique.

A search for astrophysical sources of low-energy neutrinos using the IMB detector

view Abstract Citations (7) References (12) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Search for Astrophysical Sources of Low-Energy Neutrinos Using the IMB Detector Miller, R. S. ; Becker-Szendy, R. ; Bratton, C. B. ; Breault, J. ; Casper, D. ; Dye, S. T. ; Gajewski, W. ; Goldhaber, M. ; Haines, T. J. ; Halverson, P. G. ; Kielczewska, D. ; Kropp, W. R. ; Learned, J. G. ; Losecco, J. ; Matsuno, S. ; Matthews, J. ; McGrath, G. ; McGrew, C. ; Price, L. ; Reines, F. ; Schultz, J. ; Sinclair, D. ; Sobel, H. W. ; Stone, J. L. ; Sulak, L. R. ; Svoboda, R. ; van der Velde, J. C. Abstract The temporal structure of low-energy (20 to 60 MeV) neutrino interactions within the Irvine-Michigan-Brookhaven-3 (IMB-3) detector during 863 days of livetime between 1986 May and 1991 March has been analyzed. The neutrino data are consistent with expected cosmic-ray-induced neutrino interactions with no bursts evident (excluding SN 1987A). When combined with the 327 effective livedays of IMB-1 data, we place a 90% C.L. upper limit of less than or equal to 0.71 Galactic supernovae/yr. We have also performed a temporal correlation analysis with gamma-ray bursts (GRBs) using a subset of the low-energy neutrino data. No significant correlations were observed for coincidence windows of 1 minute, 1 hour, or 1 day. Publication: The Astrophysical Journal Pub Date: June 1994 DOI: 10.1086/174272 Bibcode: 1994ApJ...428..629M Keywords: Cosmic Rays; Gamma Ray Bursts; Neutrinos; Radiation Sources; Supernovae; Ginga Satellite; Monte Carlo Method; Photomultiplier Tubes; Solar Maximum Mission; Temporal Resolution; Astrophysics; ELEMENTARY PARTICLES; ISM: COSMIC RAYS; GAMMA RAYS: BURSTS; STARS: SUPERNOVAE: GENERAL full text sources ADS | data products SIMBAD (1)

Correlation between gravitational-wave detectors and particle detectors duringSN1987A

A review of the correlations between gravitational-wave detectors and particle detectors during SN1987A is given. The correlation between the Maryland and Rome g.w. detectors with the Mont Blanc neutrino detector is illustrated. This correlation extends during a period of one or two hours centred at 2:45 UT of 23 February 1987, with the «neutrino» signals delayed by (11 ± 0.5) s and with a probability of the order of 10-5 to be accidental. Using the data obtained with the Kamiokande and IMB detectors, with the same statistical choices and procedures for the data analysis used previously, the above result is confirmed with a probability of the order of 10-3 or 10-4 that the additional correlation be accidental.

A search for oscillation of atmospheric neutrinos with the IMB detector

Neutrino oscillations have been studied using a flux of atmospheric neutrinos and the IMB water C̄erenkov detector. The study is based on: 1) a sample of 935 events in the detector volume during 7.7 kton-yrs exposure. About 70% of events have a single track which allows identification of the parent neutrino flavor. 2) a sample of 593 up-going muon tracks from neutrino interactions in rock below the detector. These studies are sensitive to δm 2 down to 10 −4 eV 2 and sin 2 (2 θ ) > 0.4, a region unexplored in previous experiments. Future plans of long baseline neutrino oscillation studies using the IMB detector and neutrinos from artificial sources are described. They include ν e from a power reactor 13 km from the detector and ν μ produced by the Main Injector at Fermilab at a distance of 570 km.

Natural framework for solar and 17-keV neutrinos.

Motivated by recent experimental claims for the existence of a 17 keV neutrino and by the solar neutrino problem, we construct a class of models which contain in their low-energy spectrum a single light sterile neutrino and one or more Nambu-Goldstone bosons. In these models the required pattern of breaking of lepton-number symmetry takes place near the electroweak scale and all mass heirarchies are technically natural. The models are compatible with all cosmological and astrophysical constraints, and can solve the solar neutrino problem via either the MSW effect or vacuum oscillations. The deficit in atmospheric muon neutrinos seen in the Kamiokande and IMB detectors can also be explained in these models.

Has supernova SN1987 A provided the lifetime of the 17 keV neutrino?

It is suggested that the late neutrino events from supernova SN 1987 A detected by the Kamiokande and IMB detectors can be understood as arising from massive neutrinos decaying in flight. If the neutrino mass is 17 keV, the estimated mean life is (0.6–1.6) x 10 4s. The shorter prompt pulse then implies an upper limit to the mass of the lightest neutrino of 13 eV.

Search for Cygnus X-3 in underground muons during the 1989 radio outbursts using the IMB detector.

A search is made for underground muons from Cygnus X-3 with the Irvine-Michigan-Brookhaven IMB-3 detector around the time of the 1989 radio outbursts. No long-term pulsed signal is found in a sample of 11 117 underground muons collected from the direction of Cygnus X-3. We place an upper limit of 3{times}10{sup {minus}10} cm{sup {minus}2} sec{sup {minus}1} on the flux of underground muons from Cygnus X-3.

Experimental status of high energy neutrino astronomy

Current status of high energy astronomy is reviewed from an experimental point of view. Present data from the Baksan, Kamiokande, and IMB detectors constrain neutrino flux enhancement factors (λ) to be less than about 400, based on extrapolations from reported ultrahigh energy (UHE) “D.C.” gamma ray observations.

A statistical analysis of angular distribution of neutrino events observed in Kamiokande II and IMB detectors from supernova SN 1987 A

A detailed statistical analysis of angular distribution of neutrino events observed in Kamiokande II and IMB detectors on UT 07∶35, 2/23'87 is carried out. Distribution functions of the mean scattering angles in the reactions\(\bar \upsilon _e p \to e^ + n\) andve→ve are constructed with account taken of the multiple Coulomb scattering and the experimental angular errors. The Smirnov and Wald-Wolfowitz run tests are used to test the hypothesis that the angular distributions of events from the two detectors agree with each other. We test with the use of the Kolmogorov and Mises statistical criterions the hypothesis that the recorded events all represent\(\bar \upsilon _e p \to e^ + n\) inelastic scatterings. Then the Neyman-Pearson test is applied to each event in testing the hypothesis\(\bar \upsilon _e p \to e^ + n\) against the alternativeve→ve. The hypotheses that the number of elastic events equalss=0, 1, 2, ... against the alternativess≠0, 1, 2, ... are tested on the basis of the generalized likelihood ratio criterion. The confidence intervals for the number of elastic events are also constructed. The current supernova models fail to give a satisfactory account of the angular distribution data.

Observation of SN1987A by neutrino light

On the 54th day of 1987 an event occurred on Earth which gave reality to the fifty-five year old dreams of Baade, Zwicky, and Landauan event which confirmed thoughts of Chandrasekhar and Bethe. Also confirmed were the computer-based calculations of Colgate, Arnett, Burrows, Lattimer, Weaver, Woosley, Wilson and many others. The event was the arrival of a neutrino pulse that had been rushing towards the Earth for 170 000 yr. Had it arrived a few years earlier it would have gone unrecorded. Had its source in the Large Magellanic Cloud been much further away, it would have been too feeble to see. ~1016 neutrinos passed through the IMB detector (in the United States) in a few seconds. Only eight made recorded interactions. Simultaneously the Kamiokande detector (in Japan) recorded eleven. These numbers are in remarkable accord with the expectations of the above thinkers. It is a masterful triumph of the human intellect. Such pulses may pass our way every 10-100 years. *~ The chance that any more will be recorded may not be high since it requires the maintenance of large, complex detectors over these very long time periods. The detectors which recorded these events consisted of large masses of water viewed by many photomultiplier tubes located deep underground. **~ The events seen in the detectors are, individually, not very spectacular. In the IMB detector, for example, they have energies of only 20-40 MeV, close to that detector's threshold of visibility. An electron of 20 MeV will only light up approximately two dozen of the detector's 2048 phototubes. Such a signal must be picked out from a background due to radioactivity, electronic noise, and neutrino interactions from the atmospheric cosmic ray background. By appropriate filtering one can reduce the data to the cosmic ray neutrino rate, which is about two events per week in the 20-50 MeV energy band. A pulse of eight such events in six seconds is, therefore, truly extraordinary. This is what was recorded by IMB and similarly by a sequence of pulses in Kamiokande on February 23, many powers of ten above that expected from statistical fluctuations in the neutrino background.

Solar neutrino searches and cold dark matter

We consider new data on high energy neutrinos ( E v>2 Gev) obtained from the Frejus and Kamioka detectors as well as previous data from the IMB detector and compare the experimental limits on neutrinos from the sun to our expectations based on a cold dark matter hypothesis. We also extend previous work to include a wide variety of cold dark matter candidates.