Shigeki Suwa

Elastic Scattering of 14 MeV Protons by Deuterons and by Protons

The differential cross sections for the elastic scattering of 13.93 MeV protons by deuterons were measured with accuracy varying from 1 to 3% at angles from 12° to 164° in the center-of-mass system. A shallow Coulomb-nuclear interference minimum near 17° was observed. The angular distribution is in good agreement with that of neutrons scattered by deuterons at 14 MeV, although the p – d cross sections seem systematically a little smaller than the n – d cross sections at backward angles. For forward angles, the experimental results contradict with the prediction of the existing theory. The small-angle p – d elastic scattering at 10.14 MeV was also investigated and a similar shallow Coulomb-nuclear interference was observed, in contrast with the theoretical curve of Christian and Gammel. The p – p scattering experiment at 14.16 MeV is also described. Measurements were made with accuracy of 1 to 2% for angles from 30° to 114° in the center-of-mass system.

A 160 cm Synchro- and Variable Energy Ordinary Cyclotron

A 160 cm cyclotron have been constructed as the first accelerator of the Institute for Nuclear Study, University of Tokyo. This cyclotron can be used as a variable energy ordinary cyclotron as well as a synchro-cyclotron by changing the dee-system and the oscillator system. As an ordinary cyclotron it can produce protons of any desired energy between 7.5 and 15 MeV, deuterons between 15 and 21 MeV, and α particles between 30 and 42 Mev. These beams are now being used for various experiments on nuclear reactions and for production of radioisotopes. As a synchro-cyclotron, it can produce protons of 57 MeV in energy and the beam is extracted with high efficiency at a radius near n =1 with an electrostatic deflector.

A 300-MeV Proton Beam Line with Energy Degrader for Medical Science

The design of a proton beam line for medical science is presented. A proton beam of energy ranging from 150 to 300 MeV is obtained by decelerating the 500-MeV KEK booster synchrotron beam in a carbon energy degrader. Problems associated with the use of the energy degrader in the beam line are discussed in detail. The available proton intensity at 250 MeV is estimated to be 2×109 protons per pulse with a repetition rate of 20 Hz. The beam line provides an achromatic, horizontal beam and a vertical beam. The former is suitable for proton diagnosis, and the availability of both the horizontal and the vertical beam increases the usefulness of proton radiotherapy.

MEASUREMENTS OF THE POLARIZATION IN PROTON-HELIUM ELASTIC SCATTERING

The polarization of protons elastically scattered by helium was measured by the double scattering method. Incident proton or alpha-particle beam was obtained from the INSJ 160-cm variable energy cyclotron. Three interdependent measurements, in which the polarization product was equul to P/sub 1/P/sub 2/, P/ sub 2/P/sub 3/, or P/sub 3/P/sub 1/, were made. The following results were obtained: P/sub 1/(6.2 Mev, 130.0 deg ) = 0.92 plus or minus 0.11: P/sub 2/(11.5 Mev, 61.1 deg ) =--0.45 plus or minus 0.06; and P/sub 3/(9.1 Mev, 61.1 deg ) = - -0.45 plus or minus 0.06, where angles and energies are those in the center-of- mass system. Experimental values of the polarization agreed well to the values calculated by using phase shifts, which were obtained from the analysis of the angular distribution of the scattering cross sections. (auth)

Efficient beam extraction from a synchro-cyclotron at n = 1

Abstract With an electrostatic deflector placed at n = 1 (the point of maximum Br ), about 50 percent of the internal beam (inside n = 0.2) of the 260 cm synchro-cyclotron could be extracted, and most of the extracted beam was confined within a 2.5 cm diameter area at the tank exit by inserting a magnetic channel acting as a focusing lens. The homogeneity of the magnetic field is essential for this method of beam extraction. The configuration and position of the ion source, and the dee bias voltage were found to affect the transmission of the beam through n = 0.2 to n = 1. Under the optimum conditions, 70 to 80 percent of the beam inside n = 0.2 reached n = 1.

Hyperfine Structure of the Spectrum of Pr II

Analysis of the hyperfine structure of the term 4 f 3 ( 4 I )6 s of Pr II resulted a (6 s )=0.426 cm -1 , a 4 f =0.0227 cm -1 . From the value of a (6 s ) the nuclear magnetic moment of Pr was deduced to be µ=+4.0 n.m., in agreement with the value given in the literature. From the value of a 4 f the screening constant σ of the 4 f electron was deduced to be 32.9. The quadrupole moment of Pr was found to be Q =(0.0±0.2)×10 -24 cm 2 . This is in agreement with the value Q =-0.05×10 -24 cm 2 calculated from the data published by Lew regarding the hyperfine structure of the ground term of Pr I.

Hyperfine Structure of the Spectrum of Gadolinium

The hyperfine structures of 32 lines of Gd I and 2 lines of Gd II in the visible region were measured. They could be interpreted as due to the isotope displacement effect of the even isotopes (156, 158 and 160) and the splittings due to the nuclear magnetic moments of the odd isotopes (155 and 157). The ratio of the isotope displacements Δ (158-156)/ Δ (160-158)=0.97±0.06 was determined. The relative isotope displacement Δ (160-158) in some 30 terms of Gd I is tabulated.

Das Bogenspektrum des Jods und das Quadrupolmoment von J127

ZusammenfassungAls Fortsetzung der früheren Arbeit wurde das Spektrum J I analysiert und die Hyperfeinstruktur wurde gemessen. Aus den Termen 6s4-P5/2 und 6s4-P3/2 ergibt sich das Quadrupolmoment von J127 zu (−0,72±0,02) · 10−24cm2.

Revision of the Hyperfine Structure of the Mercury Spectrum

The hyperfine structure of λ 5790, λ 5789.7, λ 5769 and λ 4047 of the spectrum of Hg I was studied, and the structure of some terms was determined. The ratio of the hyperfine structure constant of Hg 199 to that of Hg 201 was calculated for the terms 6 p 1 P 1 , 6 p 3 P 2 and 7 s 3 S 1 , and it was found that the ratio is anomalous for the term 6 p 1 P 1 . The quadrupole moment of Hg 201 was calculated to be 0.3 5 ·10 -24 cm 2 . Regularity in the displacement of even isotopes in lines of the mercury spectrum was found to exist in such a way that the ratio of the spacings Hg 204 –Hg 202 : Hg 202 –Hg 200 : Hg 200 –Hg 198 is constant for all lines examined and is equal to 1 : 0.933 : 0.880. The same qualitative regularity was found in the isotopic displacement in lines of heavy elements consisting of at least three even isotopes.

Protons from the p + d Breakup Reaction at Proton Energies of 14 MeV and 10 MeV

The energy spectra of the protons from the p + d breakup reaction as a function of angle were measured for the incident proton energies of 13.9 MeV and 10.1 MeV, using a particle selecting counter telescope consisting of a three- or five-layer proportional counter for the energy loss measurement and of an NaI scintillation counter for the energy measurement. Each of the observed energy spectra shows a rather steep rise at the maximum energy followed by a slight shoulder at large angles at the incident proton energy of 14 MeV, while the energy spectra at small angles do not show such shoulder. For both energies, each of the spectra has a maximum in its low energy side.