J. J. Simpson

A Heavy Water Detector to Resolve the Solar Neutrino Problem

Abstract The observation of the following three reactions: νed→ppe; νxe→νxe; and νxd→νxpn (where νx is any left- handed neutrino) in a heavy water Cerenkov detector which is being designed, allows the solar 8B ve flux, spectrum and direction to be measured. In addition, the total solar 8 Bν c neutrino flux, direction and integral spectrum, independent of neutrino flavor, may be determined to provide several independent methods to resolve the solar neutrino problem.

Lifetimes of 44Ti Levels

Abstract Lifetimes in 44 Ti have been measured by the attenuated Doppler shift following α-capture in 40 Ca. targets. Mean lifetimes for the 1083 keV (2 + 1 ), the 2454 keV (4 + 1 ), the 2531 keV (2 + 2 ), the 2886 keV (2 + 3 ) and the 3415 keV states of 44 Ti are respectively 4.5 ± 1.1, 0.60 ± 0.11, 1.42 ± 0.20, 0.42 ± 0.14 and 0.70 ± 0.11 ps. The lifetimes of the 1904 keV (0 + 2 ) and 3176 keV states are greater than 0.7 and 3.0 ps, respectively. The level energies and experimental B (E2) values support the vibrational model as a first approximation for 44 Ti. On the other hand the strong 2 + 2 → 0 + 2 transition (24 ± 6 W.u.) suggests the beginning of a rotational band based on a deformed panicle-hole configuration.

Decay of the compound nucleus 74Kr formed in the reaction 16O + 58Ni

Abstract Gamma-ray and charged-particle emission has been studied after bombardment of 58 Ni with 16 O at energies from 44.5–76.5 MeV. The excitation functions for various reaction channels have been measured. The locus in energy and spin of maximum cross section (the entry line) of the γ-emitting region in the 2pγ and 3pγ channels have been studied through measurement of γ-ray multiplicity, average particle energy and average γ-ray energy. The standard deviations in both energy and spin of the distributions of cross section are presented. Statistical model calculations including shell corrections in the level density show very satisfactory agreement with the experimental results. The moment of inertia at high spin and excitation energy is deduced from the measured entry line.

Is there evidence for a 17 keV neutrino in the 35S β spectrum? The case of Ohi et al.

Abstract It is shown that there is a threshold 17 keV below the end point of the β spectrum of 35 S in the published work of Ohio et al. The distortion of the Kurie plot is consistent with that seen in the 3 H β spectrum, strengthening the earlier suggestion that the distortion is due to the emission of a neutrino of mass 17 keV.

Intensity of the 1001 keV γ-ray in the decay of234mPa

The intensity of the 1001 keV γ-ray occurring in the decay of234mPa in equilibrium with natural uranium sources is found to be (0.818±0.030)%. This value is in agreement with a recent measurement employing depleted uranium sources, but does not agree with earlier reports employing radiochemically pure sources.

Neutron-activation analysis of thorium in acrylic samples

The techniques employed to measure Th concentrations in acrylic (PMMA) samples at a level of a few tens of ppt are described. Measurements on eleven different acrylic samples yielded a mean Th concentration of 40±20 ppt.

Spins of the 3176 and 3646 keV levels of 44Ti

Abstract The available evidence on the spin-parity assignments for the 3176 and 3646 keV levels of 44 Ti is reviewed. The results of new studies of the decay γ-rays of the 4.22 MeV resonance in the 40 Ca(α, γ) 44 Ti reaction are presented. Angular distribution fits and strength arguments are used to establish J (3176) = 3 and J (3646) = 4, with the two levels having the same parity. If the 46 Ti(p, t) 44 Ti reaction excites only states of natural parity, then J π (3176) = 3 − and J π (3646) = 4 − .

Limits on massive Majorana neutrinos from neutrinoless double β-decay

It is pointed out that present lower bounds on the lifetime for neutrinoless double β-decay put stringent upper limits on the mixing of a heavy Majorana neutrino (< a few MeV) with the dominantly coupled light neutrino of β-decay.

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

Abstract 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 4 s. The shorter prompt pulse then implies an upper limit to the mass of the lightest neutrino of 13 eV.

The Sudbury D2O Neutrino Detector

The construction of a solar neutrino observatory in a nickel mine near Sudbury, Canada, has been proposed[1]. This proposal is both attractive and timely because of the temporary surplus of over 1000 Mg of D2O stockpiled for the Canadian-designed nuclear power reactors, of the large rock overburden at the INCO mine and of the scientific interest in the solar neutrino flux and neutrino oscillations. The primary objective of the experiment is to measure the incident electron neutrino (νe) spectrum above 5 MeV in real time with energy and directional resolution. It is also expected that the total neutrino (νx) flux above 2.2 MeV can be measured thereby providing important information concerning neutrino oscillations. The observatory will also be a sensitive instrument for measuring neutrinos produced by cosmic rays, solar flares and collapsing stars.