Y. Tagishi

A Lamb-shift polarized ion source for the Tandem Accelerator Center, The University of Tsukuba

Abstract Characteristic features are given for the Lamb-shift polarized ion source at the Tandem Accelerator Center, The University of Tsukuba. A spin-filter polarization method is used. This source has been in operation with the 12 UD Pelletron tandem accelerator since 1976. The beam intensity available on target is 100 nA with polarizations of 85% for protons and 80% for deuterons.

Tensor interaction in elastic scattering of polarized deuterons from medium-weight nuclei near Ed = 22 MeV

Abstract Differential cross section σ(θ), vector analyzing power iT 11 ( θ ) and all three tensor analyzing powers T 20 ( θ ), T 21 ( θ ), and T 22 ( θ ) have been measured for elastic scattering of deuterons from twelve medium-weight nuclei 40 Ca, 58,60,62,64 Ni, 90 Zr, 92,100 Mo, and 104, 106, 108, 110 near E d = 22 MeV. Scattering angles were covered over a wide range from θ = 30° to 170°. The data were analyzed in terms of an optical model potential including a complex tensor interaction of the type T r . The tensor analyzing power T 21 ( θ ) and the quantity X 2  T 22 (θ)-√ 3 2 T 20 (θ) play an essential role in extracting the tensor interaction and its strength. The obtained T r tensor potential has the real (imaginary) part with well depth, radius, and diffuseness parameters of 1.0 ~2.5 MeV (1.0~ 2.5 MeV), 1.0 ~1.5 fm (0.9~1.2 fm), and 0.4~0.6 fm (0.8 ~ 1.7 fm), respectively. The imaginary T r potential has larger diffuseness than the real one. In extracting these parameter values the T 21 ( θ ) data of the backward angular region (100° ≲ θ ≲ 170°) are indispensable. The optical potential thus obtained is compared with a folding model potential. The effect of the tensor potentials of the types T P and T L was investigated.

Tables of linear-polarization mixing coefficients☆

Abstract Linear-polarization mixing coefficients for mixed dipole and quadrupole γ radiations have been listed as functions of mixing ratios for integer and half-integer spins up to 26. A familiar type of the Compton polarimeter is briefly discussed in connection with these coefficients.

Analyzing powers for the (p, α) reactions on 58, 60, 62Ni at Ep = 22 MeV

Measurements of both the analyzing power and cross section were made for the (p, α) reactions on 58,60,62Ni at an incident energy of 22 MeV. Data were taken for the strongly populated proton-hole states (0f72, 1s12 and 0d32) in the residual cobalt isotopes and for 8 weakly populated low-lying states in 55Co and 59Co. Angular distributions were taken between θlab = 10° and 140° for the ground state and θlab = 10° and 80° for the excited states. Both the cross sections and analyzing powers exhibit a similar angular distribution for states having the same Jπ values except in the transition to the 32− state in 59Co at 1.099 MeV. Using the observed J-dependence of the analyzing power, the unknown Jπ values for the states at 2.982 MeV in 55Co and 3.090 MeV in 59Co are assigned to be 92−. The shapes of the differential cross sections were well reproduced by the zero-range DWBA calculations using a triton-cluster form factor. However, all the measured analyzing powers could not be reproduced within the framework of such a simple DWBA calculation.

Deuteron elastic scattering and (d, p) reactions on 208Pb at Ed = 22 MeV and j-dependence of T20 in (d,p) reaction

Abstract An experimental study of deuteron elastic scattering and (d,p) reactions at E d = 22 MeV was made for 208 Pb target. A new j -dependence of T 20 for (d,p) reaction at backward angles was observed. A “model independent” optical potential method was applied to analyze deuteron elastic scattering in the 10–22 MeV energy range. A continuum discretized coupled channels (CDCC) analysis was performed for deuteron elastic scattering at 22 MeV and the deuteron breakup effect was elucidated. DWBA and CDCC (d,p) analyses were made for (d,p) reactions.

Test of phototube bases for high counting rates

Abstract We report on test measurements of the counting efficiency using a newly developed miniature photomultiplier R1635. Two methods of the voltage stabilization have been used: (1) the emitter follower type by NPN transistors and (2) the booster type in which the constant dynode voltage is supplied from a separate power supply. The test was performed by using a light emitting diode and 10 MeV protons from a tandem accelerator. Both methods of voltage stabilization have shown good results. A counting efficiency of about 100% could be obtained up to a flux of 2×10 6 particles/s (pps) and 85% at 10 7 pps.

Analyzing Powers for (P,t) Transitions to the First-Excited 2^+ States of Medium-Mass Nuclei and Nuclear Collective Motion

Vector analyzing powers A (θ) and differential cross sections σ(θ) have been measured by use of a polarized proton beam of 22.0 MeV for ( p , t ) reactions leading to the first-excited 2 + (2 1 + ) states of the eighteen nuclei of N =50–82: 92,94,96 Mo, 98,100,102 Ru, 102,104,106,108 Pd, 110,112,114 Cd, 116 Sn, 120,126,128 Te and 136 Ba. In addition A (θ) and σ(θ) for 104,110 Pd( p , t ) 102,108 Pd(0 g + , 2 1 + ) have been measured at E p =52.2 MeV. The results are analyzed in terms of the first- and second-order DWBA including both inelastic two-step and sequential transfer ( p , d )( d , t ) two-step processes. Interference between the direct and the two-step processes is important. The nuclear-structure wave functions are constructed under the boson expansion method and the quasiparticle random phase approximation method.

The fluorescent decay of CsI(Tl) scintillator for charged particles of different ionization density

We have measured the fluorescent decay times in a CsI(Tl) scintillator as a function of energy deposits in it between 1.6 and 30 MeV. The emission probability is an increasing function of the stopping power dE/dx and saturates at dE/dx ∼ 1000 MeV/cm.

Mechanism of (d, α) reaction: 208Pb(d, α)206Tl and 90Zr(d, α)88Y using vector- and tensor-polarized deuterons

Abstract Differential cross sections σ, vector- and tensor analyzing powers iT11, T20, T21 and T22 for the reactions 208 Pb ( d , α) 206 Tl ( gs. 0 − ) and 90 Zr ( d , α) 88 Y ( gs . 4 − and first excit measured near Ed = 22 MeV. Since the transition 208Pb (d, α)206Tl(0−) has a special spin- and parity sequence 1+ + 0+ → 0+ + 0−, its transition matrix has only two independent complex elements: the one is spin-state changed and the other spin-state unchanged. Thus the transition matrix has been completely determined in terms of three observables σ, iT11 and T20, i.e., a complete experiment has been carried out. The data for the (d, α) reactions on 208Pb and 90Zr have been analyzed by the method of the first- and second-order finite-range distorted wave Born approximation. The reaction 208 Pb ( d , α) 206 Tl (0 − )[ 90 Zr ( d , α) 88 Y (4 − and 5 − )] is an angular-momentum mi [matching] transition. Both reactions have been explained in terms of the sequential transfer ( d, t )( t , α) and ( d , 3 He )( 3 He , α) two-step processes in addition to a (d, α) one-step process which includes the α-particle S- and D-state components.

Real-time measurement of implanted deuterons by using the nuclear reaction 2H(d, p)3H

Abstract We propose a method for real-time measurement of the density of implanted deuterons in solid materials during deuterium implantation. In this method, the density of implanted deuterons is measured by detecting the emitted protons from the deuteron fusion reaction between the incident deuterons and the implanted deuterons. A negative deuterium beam with an energy of 90 keV is used both for the implanted atoms and a probe beam to measure the implanted deuterons. The density of the implanted deuterium atoms was observed to be drastically different between the single crystal and poly-crystal in Ta.