Haruko Ohmura

The (3He, d) reaction on 116Sn, 118Sn and 120Sn

Abstract The (3He, d) reaction on 116Sn, 118Sn and 120Sn has been studied with 28.2 MeV 3He particles. Deuteron spectra have been measured with a broad-range magnetic spectrograph. Information on the nuclear structure of 117Sb, 119Sb and 121Sb has been obtained from the distorted-wave Born-approximation analysis of angular distributions of various deuteron groups. The 11 2 − state has been located at 1.32, 1.37 and 1.42 MeV in 117Sb, 119Sb and 121Sb, respectively. The lowest lying 5 2 + , 7 2 + and 11 2 − states in each of the three nuclei have been found to be of rather pure single-particle character, whereas the lowest lying 1 2 + and 3 2 + states are found to be seriously mixed.

1 g/sub 9/2/ neutron state in nuclei with neutron numbers between 52 and 82

Spectra of deuterons from (p d) reactions on 18 nuclei with neu tron numbers N between 52 and 82 were measured at an angle of 20 deg with 52-MeV incident protons. In each spectrum a broad bump with the distinct top is observed at excitation energies of several MeV or higher. From the systematic behavior of the bump it is inferred that the top of the bump stands for an approximate position of the 1g/sub 9/2/ neutron state, and energies of this state are estimated from the observed spectra. The estimated energies are compared with calculated ones and a reasonable agreement is obtained. The systematics of the enengy diffurence between the top of the bump and the ground state in the residual nucleus is discussed on the basis of the simple pairing theory, and results which are well consisient with the above interference about the top of the bump are obtained. (auth)

Some evidence for neutron pick-up from the interior core through the (p, d) reaction

Abstract The (p, d) reactions on 94, 98, 100 Mo were studied with 52 MeV protons. Deuteron spectra were measured up to 12 MeV of excitation in the residual nuclei. The angular distributions for the three reactions integrated over the final levels in a range of excitation from 2 to 6 MeV are in good agreement with each other, though the relevant parts of the deuteron spectra apparently show isotope-dependent structures. From a comparison of the results obtained in this study with those from the (p, d) reactions on neutron closed-shell nuclei 90 Zr and 92 Mo, it is indicated that the (p, d) transitions to the levels in this particular range of excitation in 93, 97, 99 Mo are mainly due to neutron pick-up from the N = 29–50 major shell and that the transition strengths integrated over these transitions are in fair agreement with the sum-rule limit. A comparison is also made between the results obtained in this study and those from the (p, d) reactions on 117, 118 Sn, from which it is suggested that the broad peaks found in the deuteron spectra from the latter two reactions at excitation energies between 7–12 MeV in 116 Sn and 5–10 MeV in 117 Sn are mainly due to neutron pick-up from the N = 29–50 shell. Again, the transition strengths for the broad peaks are estimated to be in fair agreement with the sum-rule limit.

A NUCLEAR STRUCTURE STUDY OF

Deuterons from the ( 3 He, d) reaction on N =82 nuclei 140 Ce and 142 Nd have been measured at an incident energy of 27.30 MeV with a broad-range magnetic spectrograph. Up to 3 MeV of excitation, levels of 141 Pr at energies 0.0, 0.15, 1.14, 1.32 and 1.64 MeV and those of 143 Pm at 0.0, 0.28, 0.96, 1.17 and 1.40 MeV were observed. The differential cross sections for the transitions were analyzed with distorted-wave calculations. Values of the orbital angular momentum of the transferred proton and the spectroscopic factors of the transitions were obtained.

sup 141

Abstract The excited states in 29P have been investigated using the reaction 28Si(p, γ)29P for proton energies between 1.3 MeV.and 3.2 MeV. Gamma rays from the resonances at 1.383±0.003 MeV 1.655±0.005 MeV, 2.086±0.006 MeV, 2.88±0.02 MeV and 3.111±0.006 MeV have been studied. These resonances correspond to the excited states in 29P at 4.082±0.01 MeV, 4.345±0.01 MeV, 4.761±0.01 MeV, 5.53 MeV and 5.751±0.01 MeV, respectively. Gamma rays from the 4.08 MeV state lead to the excited states at 1.38 MeV and 1.96 MeV. The radiation widths are 0.9±0.4 meV and 1.1±0.5 meV, respectively. The 4.35 MeV state de-excites to the ground state and the first excited state with radiation widths 1.8±0.4 eV and 0.26±0.1 eV, respectively. The 4.76 MeV state showed the gamma radiation feeding the excited state. The radiation width is 0.33±0.1 eV. Capture gamma rays were not observed at 2.88 MeV resonance. Gamma transition widths from the 5.75 MeV state to the first and the second excited states are estimated to be less than 0.06 eV and not more than 0.08 eV, respectively. The analysis of angular distributions of the de-excitation gamma rays are consistent with the assignment of J π = 7 2 + ( 5 2 + ) and 3 2 − to the 4.08 MeV and 4.35 MeV states. Proton widths Γp were obtained to be less than 3 keV, 56±6 keV, 18±5 keV and 4.5±1.5 keV for the states at 4.08 MeV, 4.35 MeV, 4.76 MeV and 5.75 MeV, respectively. Properties related to the collective motion as well as the individual particle motion are found in the low-lying excited states in 29P.

Pr AND

The angular distributions of the long-range alpha particles from the reaction F/sup 19/+p, leading to the ground state of the residual nucleus O/sup 16/, have been measured. The energies of protons covered a range from 630 to 1460 kev, and measurements were made in steps of 5 to 10 kev with a proton energy spread of 0.2 per cent. Coefficients in the Legendre polynomial expansion of the anguular distribution function were traced in this range. (auth)

sup 143

The low-lying states in 29 P were excited by the reaction 28 Si( 3 He, d) 29 P. The analysis of the reaction in terms of the direct reaction process yielded the orbital angular momenta of the transferred protons and the relative values of the proton widths. The reduced proton width obtained from the experiment are generally in agreement with the values predicted on the Nilsson model with small deformation. A number of low-lying levels were found to have very small proton widths. This fact is accounted for as the effects of the rotational excitation and the band mixing of the excited levels. The measurement of the nucleon width may be useful to clarify the property of the excited level.

Pm USING THE (

SummaryAngular distributions of the α-particle groups in the40Ca(3He, α)39Ca reaction were measured atEL(3He)=24.4 MeV by the use of a broad range magnetic spectrograph. α-particle groups corresponding to excitation energies in39Ca of 0, 2.47±0.03, 2.80±0.03, 3.03±0.05, 3.95±0.03, 4.02±0.03, 5.07±0.05, 5.40±0.05, 5.70±0.1 and 6.05±0.05 MeV were observed. The DWBA analysis shows that the ground state and the first excited (2.47) state consist mainly of a (1d1/2)−1 and a (2s)−1-neutron hole state, respectively. The (1d5/2)−1 hole state is considered to split into the 5.07, 5.40 and 6.05 MeV levels with nearly equal fractions. The angular distribution corresponding to the 2.80 MeV level suggests anl=3 neutron pick-up, which is due to the configuration mixing with 1f7/2 neutron shell in the ground state of40Ca.RiassuntoSi sono misurate le distribuzioni angolari dei gruppi di particelle α nella reazione40Ca(3He, α)39Ca adEL(3He)=24.4 MeV con l’uso di uno spettrografo magnetico a larga banda. Si sono osservati gruppi di particelle α corrispondenti ad energie di eccitazione nel39Ca di 0, 2.47±0.03, 2.80±0.03, 3.03±0.05, 3.95±0.03, 4.02±0.03, 5.07±0.05, 5.40±0.05, 5.70±0.1 e 6.05±0.05 MeV. L’analisi DWBA mostra che lo stato fondamentale e il primo stato eccitato (2.47) consistono principalmente di uno stato (1d3/2)−1 e di uno stato (2s)−1 neutrone-vacanza, rispettivamente. Si ritiene che lo stato (1d3/2)−1 vacanza si scinda nei livelli di 5.07 MeV, 5.40 MeV e 6.05 MeV in parti quasi uguali. La distribuzione angolare corrispondente al livello di 2.80 MeV suggerisce un pick-up neutronicol=3, che è dovuto alla mescolanza di configurazioni con lo stato neutronico 1f7/2 nello stato fondamentale del40Ca.

sup 3

The reations Si>s2/sup >(/ gamma )P>s2/sup >,/>s2/sup > / (p, gamma )P>s3/sup >,/nd Si>s3/sup >(/ gamma )P>s3/sup > / are studied in the region of proton energy from 300 to 1700 kev. Two new resonances were found in the reaction Si>s2/sup >(/ gamma )F>s3/sup > / proton energies 1307.5 plus or minus 3 and 1331.5 plus or minus 3 kev, and in the reaction Si>s3/sup >(/ gamma )P>s3/ sup > /ne new resonances were found at proton energies 1094, 1179.5, 1209.5, 1290.5, of plus or minus 3 kev. No definite resonant level was observed in the reaction Si>s2/sup >(/ gamma )P>s2/sup > / the range of proton energy between 570 and 1400 kev. (auth)The reactions 28 Si( p , γ) 29 P, 29 Si( p , γ) 30 P and 30 Si( p , γ) 31 P have been studied in the region of proton energy from 300 kev to 1700 kev. We have found in the reaction 29 Si( p , γ) 30 P two new resonances at proton energies 1307.5±3 kev and 1331.5±3 kev, and in the reaction 30 Si( p , γ) 31 P nine new resonances at proton energies 1094, 1179.5, 1209.5, 1290.5, 1300, 1302.5, 1324.5, 1394.5 and 1403 kev with the errors of ±3 kev. No definite resonant level has been observed in the reaction 28 Si( p , γ) 29 P in the range of proton energy between 570 kev and 1400 kev.

He,d) REACTION ON

The spin of Ag/sup 110m/ (253 days) was recently detcrmined as 6 by the atomic beam magnetic resonance method. Since a previous analysis, concerning the angular correlation measurement of gamma rays from this nucleus, was based upon the assumption of 5 or 4 for the spin and parity of this level, it was considered worthwhile to reexamine the results. (W.D.M.)