T. J. Bowles

Measurement of the response of a Ga solar neutrino experiment to neutrinos from an 37Ar source

An intense source of 37Ar was produced by the (n, α) reaction on 40Ca by irradiating calcium oxide in the fast neutron breeder reactor at Zarechny, Russia. The 37Ar was released from the solid target, sealed into a small source, and was used to irradiate 13 tonnes of gallium metal in the Russian-American gallium solar neutrino experiment SAGE. The initial source strength was 409 ± 2 kCi. The measured production rate of 71Ge on gallium metal was 11.0+1.0−0.9 (stat) ± 0.6 (syst.) atoms per day, which is 0.79+0.09−0.10 of the theoretically calculated production rate.

Quantum effects of gravity.

The effects of gravity and quantum mechanics rarely overlap because of the different scales involved. An experiment with ultracold neutrons has now been able to probe both simultaneously.

First results from the Soviet-American gallium experiment

Abstract The Soviet-American Gallium Experiment is the first experiment able to measure the dominant flux of low energy p-p solar neutrinos. Four extractions made during January to May 1990 from 30 tons of gallium have been counted and indicate that the flux is consistent with 0 SNU and is less than 72 SNU (68% CL) and less than 138 SNU (95% CL). This is to be compared with the flux of 132 SNU predicted by the Standard Solar Model.

Neutrino properties and puzzles

Abstract Sixty years after the existence of the neutrino was first postulated, we are still lacking in information on the fundamental properties of neutrinos. Measurements have consistently pushed the limits on the mass, magnetic moment and possible mixing down. Solar neutrino experiments are now shedding more light on the “solar neutrino problem” and are starting to give a hint that perhaps these quantities are nonzero. The present status of our knowledge of neutrino properties, the newest experimental data on the “solar neutrino problem,” and future plans are presented.

The Baksan Gallium Solar Neutrino Experiment

A radiochemical 71Ga-71Ge experiment to determine the integral flux of neutrinos from the sun has been constructed at the Baksan Neutrino Observatory in the USSR. Measurements have begun with 30 tonnes of gallium. The experiment is being expanded with the addition of another 30 tonnes. The motivation, experimental procedures, and present status of this experiment are presented.

Status of the Soviet‐American gallium experiment

A radiochemical 71Ga‐71Ge experiment to determine the primary flux of neutrinos from the Sun has begun operation at the Baksan Neutrino Observatory in the USSR. The number of 71Ge atoms extracted from thirty tons of gallium was measured in five runs during the period of January to July 1990. Assuming that the extraction efficiency for 71Ge atoms produced by solar neutrinos is the same as natural Ge carrier, this corresponds to a limit on the product of the neutrino flux and the cross section for all sources of neutrinos of less than 72 SNU (90% CL). This is to be compared with the flux of 132 SNU predicted by the Standard Solar Model.

Neutrino mass and dark matter

The existence of a finite neutrino mass would have important consequences in particle physics, astrophysics, and cosmology. Experimental sensitivities have continued to be pushed down without any confirmed evidence for a finite neutrino mass. Yet there are several observations which might be possible indications of a finite neutrino mass. If these hints are confirmed, then it is likely that at least one of the neutrinos has a mass in the eV range. As such, it would be a prime candidate for the hot dark matter that seems to be required to explain a number of observations of the large‐scale structure of the Universe.

The status of the Soviet - American gallium neutrino experiment

Abstract A radiochemical 71Ga-71Ge experiment to determine the integral flux of neutrinos from the sun has been constructed at the Baksan Neutrino Observatory in the USSR. Measurements have begun with 30 tonnes of gallium. An additional 30 tonnes of gallium are being installed so as to perform the full experiment with a 60 tonne target. The motivation, experimental procedures, and present status of this experiment are described.