T. Sakae

Elastic scattering of electrons by water molecules over the range 100-1000 eV

Relative values of differential cross sections (DCS) are measured by the crossed-beam method. Two cylindrical-mirror energy analysers are employed. One of them is moved to detect scattered electrons at every angle, and the other is fixed at an angle to monitor the elastic scattering events. The effects of target gas distributions in a molecular beam flowing out from a multicapillary array are taken account of to correct the relative values. The DCS are also measured at an angle for water molecules and helium atoms by using gas chamber. On the basis of the absolute DCS for He measured by Jansen et al. (1976), the relative DCS for water molecules are converted into absolute values. In addition, the DCS are calculated by the partial-wave method for the double Yukawa potential. The values of its three adjustable parameters are determined by comparison with the experimental DCS. A spherically symmetric realistic potential is also inferred without adjustable parameters from the charge distribution that was derived from molecular-orbital theory. The DCS calculated for this potential reproduce the experimental values fairly well.

Observation of Self-Quenching Streamers in Quenching Gases of Hydrocarbons and Carbon Dioxide

Basic properties of the self-quenching streamer transition have been studied for quenching gases of CH/sub 4/, C/sub 2/H/sub 6/, C/sub 3/H/sub 8/, isoC/sub 4/H/sub 10/ and CO/sub 2/ without argon. It is found that X-rays do not induce clearly the transition, but ..cap alpha..-rays, which are incident in normal to the counter anode, induce it evidently in all the quenching gases. This suggests that argon is important but is not essential to obtain the transition. Instead of energetic photons from excited argon molecular states for the transition, possible origins of energetic photons in the quenching gases are discussed.

Three Dimensional Monte Carlo Simulation of the Electron Avalanche Around an Anode Wire of a Proportional Counter

A three-dimensional Monte Carlo simulation code) has been written, which calculates physical characteristics of the electron avalanche around an anode wire of a proportional counter. The microscopic treatment of the avalanche development in a gas counter has been realized first using the present simulation code. Typical results of simulations are reported.

Charge-division type position sensing with a single-wire position sensitive counter in the self-quenching streamer mode☆

Abstract Using single-wire position sensitive counters with a stainless-steel anode wire of 25 μm diameter, position sensing has been performed in the self-quenching streamer (SQS) mode. Overall position resolutions of 0.26 mm and 0.69 mm fwhm for 4.5 keV X-rays were obtained for 100 mm long and 1.82 m long counters, respectively, by means of standard NIM electronic circuits and a new ratio-to-digital converter (RDC). Problems in the application of SQS mode to position sensing are discussed.

Single-particle strengths measured with 48Ca(d, p)49Ca reaction at 56 MeV

Single-particle states in 49Ca have been investigated through the 48Ca(d, p)49Ca reaction initiated by vector-polarized deuterons of Ed = 56 MeV. Thirty-six levels were observed up to 8 MeV excitations. Transferred l, j values were deduced for these levels by measured angular distributions of cross section and analyzing power. We observed many additional states and corrected some previous jπ assignments. The total values of spectroscopic factors C2S obtained with zero-range distorted-wave-Born-approximation (DWBA) calculations are almost unity for the shells 2p32, 2p12 and 1f52, and no 1f72 states are observed. It is confirmed that 48Ca has a good closed-shell structure, the feature of which is consistent with occupation probabilities predicted from an extended second RPA theory.

Semi-microscopic formula for gas gain of proportional counters

Abstract A semi-microscopic formula of Townsends first ionization coefficient α is proposed for the gas gain of a proportional counter. The electron movement in a counter is expressed in terms of cross sections of inelastic and ionization collisions with gas molecules by introducing a simple model which has four fixed parameters for a gas. The model parameters have been determined for typical counter gases. The results of gas gain calculated by the obtained formula indicate good agreement with experimental results for several filling gas mixtures at a variety of mixing ratios and for various counter geometries.

Realization of the concept of the ratio-to-digital converter (RDC)☆

Abstract The concept of the ratio-to-digital converter (RDC) has been realized. An RDC system based on a division circuit which utilizes linear discharge functions in memory condensers has been developed. The quotient from the division circuit is converted directly into a digital form. The accuracy in the quotient is better than 0.1% for the full scale, and a linearity better than 0.05% over a dynamic range of 1:20 is obtained. This performance corresponds to that of a digital division system using two 16000-channel ADCs.

Characteristics and construction of charge-division type single-wire position-sensitive proportional counter

Abstract Characteristics and construction of charge-division type single-wire position-sensitive proportional counters are described. Performances of long detectors (1.16, 1.52 and 1.82 m long and 10×30 mm 2 cross section) and short and thin detectors (32 and 43 cm long and 6×14 mm 2 cross section) are discussed.

Absolute Neutron Sensitivity of a GSO(Ce) Scintillation Detector

A detector system with a cerium-doped gadolinium orthosilicate Gd 2 SiO 5 (Ce) scintillator coupled to a photomultiplier tube was investigated in terms of an absolute sensitivity for thermal neutron detection

Strength functions of deeply bound hole states in 111, 115, 119, 123Sn

Abstract Deeply bound hole states in 111,115,119,123Sn have been investigated with high resolution (p, d) experiments at the bombarding energy of 50 MeV. The fine structure and neutron number dependence of the strength functions of the 1 g 9 2 and 2 p (2 p 1 2 + 2 p 3 2 ) hole states have been determi The resulting strength functions and the spreading widths were compared with predictions of the nuclear damping calculations by Soloviev, Stoyanov and Vdovin and by Bortignon and Broglia.