Spectroscopy of the 50Cr(d, p)51Cr reaction and the deuteron D-state effects

Analyzing powers (T₁₁, T₂₀ and T₂₂) were measured for the (d, p) reaction leading to several states of ⁵¹Cr using 12.3 MeV polarized deuterons. The experimental results were analyzed in terms of distorted-wave theory with the inclusion of the deuteron D-state. Spin assignments to several states of ⁵¹Cr were made on the basis of j-dependence of the vector and tensor analyzing powers.     

Angular distribution of polarization transfer in 2H(d, p)3H

Measurements have been made of seven polarization transfer coefficients for the ²H($\text{d}$, $\text{p}$)³H reaction. The experiment used a polarized deuteron beam from the Los Alamos Scientific Laboratory Lamb-shift polarized ion source, a liquid-nitrogen cooled deuterium gas target, a magnetic quadrupole triplet for focusing the reaction protons and a helium filled polarimeter for simultaneously measuring the proton polarization along two transverse axes. Results have been obtained at 10 MeV and for lab angles of 15, 30, 45 and 60 degrees for the vector transfer coefficients K_x^x′, K_y^y′ and K_z^x′, and the tensor transfer coefficients K_xx^y′, K_yy^y′, K_zz^y′ and K_xz^y′.     

Energy levels of 56Co studied by the 58Ni(d, α)56Co reaction near 0°

Tensor analyzing powers, T₂₀, of outgoing α-particles in the ⁵⁸Ni($\text{d}$, α)⁵⁶Co reaction at detection angles near 0° have been measured for excited states in ⁵⁶Co for beam energies of 6.75, 7.0, 7.5, 9.0 and 9.5 MeV. Thirty-seven spin-parity combinations for ⁵⁶Co excited states have been deduced. Previous J^π ambiguities for 11 of these states have been eliminated, and results in conflict with existing assignments for the levels at 3.235 and 3.378 MeV have been obtained. A search for 0⁺ states was carried out from angular distribution measurements at forward angles of the unpolarized (d, α) reaction. The combined results from this and previous experiments were found to be in reasonable agreement with calculated level schemes.     

Study of low-lying levels in 47Ca with the 48Ca(d, t)47Ca reaction

Angular distributions of cross sections [α(θ)] and vector analyzing powers [iT₁₁(γ)] have been measured for seven low-lying states or groups of states excited by the ⁴⁸Ca($\text{d}$, t)⁴⁷Ca reaction with 13.5 MeV deuterons and analyzed by the DWBA. On the basis of comparison of vector analyzing powers with DWBA calculations, spin-parity assignments have been made or confirmed for several states. Spectroscopic factors have been extracted. Angular distributions for weak states at 3.30 and 3.57 MeV excitation in ⁴⁷Ca could not be reproduced by DWBA calculations. Investigations of compound nucleus and multi-step contributions to the cross sections and analyzing powers for these states have been made by means of Hauser-Feshbach and CCBA calculations. Optical model parameters were obtained from analysis of 13.5 MeV deuteron elastic scattering cross sections and analyzing powers.     

The 4He(d, αp)n reaction at 12 and 17 MeV

The cross section and the analyzing powers A_y, A_xx and A_yy for the reaction ⁴He($\text{d}$, αp)n are studied with kinematically complete measurements at incident energies of 12 and 17 MeV. Spectral structures due to the final-state interactions and quasifree scattering are measured. A three-body model of the Faddeev type gives a satisfactory fit to the cross-section and A_y data, but it fails to fit adequately the tensor analyzing-power data. The tensor analyzing powers in the breakup process should be sensitive to the input two-body force, and that sensitivity seems to be somewhat greater near the three-body 1⁺ resonance.     

Spin assignments in 59Ni from the 58Ni(d, p)59Ni reaction

Angular distributions of the vector analyzing power and the absolute cross section were measured for the ⁵⁸Ni(d, p)⁵⁹Ni reaction at a deuteron energy of 10 MeV. The observed j-dependence of the vector analyzing power allowed unambiguous spin assignments for the following states in ⁵⁹Ni with excitation energies in $\text{MeV}\text{: 0.0,}\text{3}\text{2}{}^{\mathrm{?}}\text{; 0.341,}\text{5}\text{2}{}^{\mathrm{?}}$; $\text{0.465,}\text{1}\text{2}{}^{\mathrm{?}}\text{; 0.879,}\text{3}\text{2}{}^{\mathrm{?}}$; $\text{1.303,}\text{1}\text{2}{}^{\mathrm{?}}\text{; 1.686,}\text{5}\text{2}{}^{\mathrm{?}}\text{; 3.454,}\text{3}\text{2}{}^{\mathrm{?}}\text{; 3.858,}\text{3}\text{2}{}^{\mathrm{?}}\text{; 4.495,}\text{5}\text{2}{}^{\mathrm{+}}$. The data are well reproduced by DWBA calculations employing deuteron and proton optical model parameters obtained from analyses of elastic scattering cross sections and polarizations. A tentative spin assignment of $\text{9}\text{2}{}^{\mathrm{+}}$ is made for the level at 3.061 MeV. A $\text{5}\text{2}{}^{\mathrm{+}}$ assignment to the level at 3.538 MeV is suggested on the basis of the empirical behavior of the j-dependence of the vector analyzing power for l = 2 transitions. Measurements of the vector analyzing power for the four low-lying ⁵⁹Ni states formed by l = 1 transfer were made for angles from 2.5° to 15° using a magnetic spectrograph. A very strong j-dependence was observed for these far-forward-angle measurements in agreement with DWBA predictions.     

54Cr, 54, 58Fe, 58Ni(d,p)55Cr, 55, 59Fe, 59Ni Vector analyzing power measurements

(d, p) cross sections and vector analyzing powers have been measured at 10 MeV bombarding energy for targets ⁵⁴Cr, ⁵⁴Fe, ⁵⁸Fe and ⁵⁸Ni. The systematic behaviour of the analyzing powers with Q for states of a given J^π has been observed. Spins of a number of states in ⁵⁵Cr and ⁵⁹Fe have been deduced.     

Measurement of the analyzing power of the 3He(d, p)4He reaction below 1 MeV

The analyzing powers iT₁₁, T₂₀, T₂₁ and T₂₂ have been measured for the reaction ³He(d, p)⁴He at laboratory energies of 344, 465 and 727 keV. A polarized deuteron beam was used with quantization axis oriented perpendicular to and at 54.7° to the incident beam direction. With semi-conductor proton detectors in two perpendicular planes all four analyzing powers could be determined. The beam polarization was determined using the ³H(d, n)⁴He reaction at a mean energy of 130 keV. The uncertainty in this analyzing power and the effect on the results is discussed. The analyzing powers have been fitted to a Legendre polynomial expansion to four or five terms and the resulting coefficients tabulated. The results indicate that d-waves contribute to the reaction only through the ${}^4\text{D}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ entrance channel and their contribution falls off both above and below the $\text{3}\text{2}{}^{\mathrm{+}}$ resonance at 430 keV.     

The reaction 55Mn(d, t)54Mn

Neutron pick-up cross sections and vector analyzing powers have been measured for the reaction ⁵⁵Mn($\text{d}$, t)⁵⁴Mn at 17 MeV. The mixture of $\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ to $\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ transfer to the low-lying l_n = 1 states has been found. Evidence of the $\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ hole nature of several strong l_n = 3 states above 1 MeV has been obtained.     

Deuteron d-state effects for the reactions 117Sn(d, p)118Sn and 119Sn(d, p)120Sn

Angular distributions of the differential cross section and the three tensor analyzing powers were measured for the reactions ¹¹⁷Sn($\text{d}$, p)¹¹⁸Sn and ¹¹⁹Sn($\text{d}$, p)¹²⁰Sn at E_d = 12 MeV. In addition, excitation functions of the tensor analyzing power T₂₀ were measured at proton lab angles of 0° and 5° for energies ranging from 10 to 12 MeV. At forward angles, the tensor analyzing powers for the ground state (l_n = 0) transitions are more than an order of magnitude larger than the predictions of distorted-wave calculations which neglect the deuteron D-state. Qualitative agreement with the measurements is obtained when the D-state is included.     

Polarization transfer in the 2H(d,n)3He reaction at θ = 0°

The vector polarization transfer coefficient K_y^y′ and the tensor analyzing power A_zz have been measured for the ²H($\text{d}$$\text{n}$)³He reaction at θ = 0° over an incident deuteron energy range from 1 to 15 MeV in 0.5 MeV steps. The results agree with the previous ²H($\text{d}$$\text{n}$)³He measurements of Simmons et al. and are nearly identical to the ²H($\text{d}$$\text{n}$)³H measurements of Clegg et al. in the region of overlap. The present results provide an accurate and complete set of the observables necessary to use the ²H($\text{d}$,$\text{n}$)³He reaction as a source of polarized neutrons.     

The d52 analog strength in 59Cu

Isobaric analog states of the strongest $\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ parent states in ⁵⁹Ni were investigated in the reaction ⁵⁸Ni + p. Proton spectroscopic factors were derived whose sum was found to be in good agreement with the sum of the parent strengths. The absolute transition probability of the E1 γ-decay populating the ⁵⁹Cu ground state was estimated and compared with single-particle predictions.     

Spin assignments in 63Ni through 62Ni(d,p)63Ni

Angular distributions of vector analyzing power have been measured for the reaction ${}^{62}\text{Ni}\text{(}\text{d, p}\text{)}{}^{63}\text{Ni}$ at a beam energy of 10 MeV. The observed j-dependence of vector analyzing power allows unambiguous spin assignments to be made for the following states in ⁶³Ni (excitation energies in MeV): $\text{0,}\text{1}\text{2}{}^{\mathrm{?}}$; $\text{0.087,}\text{5}\text{2}{}^{\mathrm{?}}$; $\text{0.155,}\text{3}\text{2}{}^{\mathrm{?}}$; $\text{0.515,}\text{3}\text{2}{}^{\mathrm{?}}$; $\text{1.003,}\text{1}\text{2}{}^{\mathrm{?}}$; $\text{2.297,}\text{5}\text{2}{}^{\mathrm{+}}$; $\text{2.700,}\text{1}\text{2}{}^{\mathrm{?}}$; $\text{2.953,}\text{1}\text{2}{}^{\mathrm{+}}$; $\text{3.292,}\text{5}\text{2}{}^{\mathrm{+}}$; $\text{3.932,}\text{5}\text{2}{}^{\mathrm{+}}$; $\text{3.951,}\text{5}\text{2}{}^{\mathrm{+}}$; $\text{4.387,}\text{5}\text{2}{}^{\mathrm{+}}$. An assignment of $\text{9}\text{2}{}^{\mathrm{+}}$ is suggested for the state at 2.519 MeV. The data for the unresolved l_n = 4, 1 doublet (1.294, 1.327) MeV indicate the $\text{3}\text{2}{}^{\mathrm{?}}$ spin assignment for the 1.327 MeV state. The main features for all the data are in agreement with DWBA calculations.     

Some studies of T = 32 states in 17F

Measurements have been made of some parameters of the second and sixth $\text{T =}\text{3}\text{2}$ states in ¹⁷F. For the second state, the resonance energy was found to be E_p = 12.707 ± 0.001 MeV (E_n = 12.550±0.001 MeV), which agrees with and improves on the accuracy of earlier work. For the sixth $\text{T =}\text{3}\text{2}$ state, at E_p = 14.435 MeV, the γ-decay was determined to be predominantly γ₀ with a branch to the first excited state of Γ(γ₁)/Γ(γ₀) ≦ 0.14. Together with other work, this determines J^π to be $\text{3}\text{2}{}^{\mathrm{?}}$. The capture strength is found to be (2J + 1)Γ_pΓ_γ/Γ = 11.4 ± 2.6 eV.     

Proton hole states in 187, 189, 191Re investigated by the (t, α) reaction

Proton hole states in ¹⁸⁷Re, ¹⁸⁹Re and ¹⁹¹Re have been studied using the ($\text{t}\text{, α}$) reaction. Beams of 17 MeV tritons with a polarization of 0.75 were obtained from the tandem Van de Graaff accelerator at the Los Alamos Scientific Laboratory. The α-particles were detected in a Q3D magnetic spectrometer with a helical-cathode position-sensitive proportional counter. Spectra were recorded up to > 2 MeV excitation energy with a resolution (FWHM) of ≈ 20 keV. These measurements exhibit large analyzing powers for transitions to well-known states in the deformed nuclide ¹⁸⁷Re. This is of interest because the only other single-nucleon transfer results on heavy deformed nuclei (in a ($\text{d}\text{, p}$) study of tungsten isotopes) showed “disappointingly small” analyzing powers. The ($\text{t}\text{,α}$) analyzing powers were reproduced by DWBA calculations very well. Thus other levels in ¹⁸⁷Re and many states in ¹⁸⁹Re and ¹⁹¹Re could be assigned spins and parities on the basis of angular distributions for the cross sections and analyzing powers. In particular, the present results have made it possible to determine which of the three possible interpretations suggested previously for the structure of ¹⁹¹Re is correct. The results have been interpreted within the framework of the Nilsson model, with pairing and Coriolis mixing corrections included. The energy systematics of single-quasiparticle states are well reproduced by the Nilsson model if a hexadecapole deformation is included in the nuclear potential. Finally, it has been demonstrated that the ($\text{t}\text{, α}$) reaction is an extremely useful spectroscopic tool for studies of heavy deformed nuclei.     

Analyzing power in the continuum of the (p, αx) and (p, τx) reactions on 12C, 27Al, 58Ni, 90Zr, 209Bi at Ep = 72 MeV

We have measured cross sections and analyzing powers in the continuum of the ($\text{p}$, αx) and ($\text{p}\text{, τx}$) reactions for ¹²C, ²⁷Al, ⁵⁸Ni, ⁹⁰Zr and ²⁰⁹Bi target nuclei, using 72 MeV polarized protons. The systematics we have found in the behaviour of the differential cross section and of the analyzing power of the ($\text{p}\text{, αx)}$ reaction is discussed and similarities in the shape of the ⁴He and ³He angular distributions are pointed out. For the ${}^{27}\text{Al}\text{(}\text{p}\text{, α}\text{x}\text{)}\text{and the}{}^{90}\text{Zr}\text{(}\text{p}\text{, αx)}$ reactions as well as for the ${}^{58}\text{Ni}\text{(}\text{p}\text{, τ}\text{x}\text{)}$ reaction, a comparison with theoretical predictions of recently developed direct-reaction models is presented. It is shown that the MSDR model can describe successfully the cross section and the analyzing power of the $\text{(}\text{p}\text{, α}\text{x}\text{)}$ reaction in the continuum. The influence of quasi-free processes in the $\text{(}\text{p}\text{, α}\text{x}\text{)}$ reaction is demonstrated. We have found a surprisingly large analyzing power of the $\text{(}\text{p}\text{, α}\text{x}\text{)}$ reaction at backward angles, especially for heavy nuclei, contrary to expectations from conventional preequilibrium models.     

Two-nucleon pick-up from spin-12 targets (II). 89Y

The angular distributions for the ⁸⁹Y(p, t), (p, τ), and (d, α) reactions are compared to DWBA predictions and to the data for the ⁹⁰Zr(p, t) and (d, α) reactions. Several new spins are assigned to levels of ⁸⁷Y. A weak coupling model is tested by the comparison between the reactions on ⁸⁹Y and ⁹⁰Zr, and found to fail. The (d, α) reaction is found to populate strongly levels at excitation energies of 2.70 MeV and 3.07 MeV in ⁸⁷Sr, corresponding roughly in Q-value and strength to states formed in ths ⁸⁸Sr(d, α)⁸⁶Rb reaction.     

Measurements of 12C(π+, πN)11C and 19F(π+, πN)18F cross sections near the 32, 32 resonance

Reaction cross sections for ¹²C(π⁺, πN)¹¹C at 134, 161, 177, and 200 MeV and for ¹⁹F(π⁺,πN) at 161, 177, and 200 MeV were measured by activation methods.     

Spin of deep-hole states in 111Sn via the 112Sn(d, t) reaction

Analyzing powers measured in the study of ${}^{112}\text{Sn}\text{(}\text{d}\text{,}\text{t}\text{)}\text{at}\text{40}\text{MeV}$ bombarding energy show strong J-dependence and have been used to clearly assign the spin of a number of low-lying states in the residual nucleus. At high excitation energy (3.5–6 MeV). the inner-hole strength is shared between clearly isolated peaks on one hand and a fragmented structure on the other. This work reports on the determination of the spin of the inner-hole states and consequently on a more precise measurement of the overlapping regions between $\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{, 2}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{, 2}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ Subshell components. The analyzing power data shows that the group of peaks located between 3.4 and 4.5 MeV consist of spins $\text{J =}\text{9}\text{2}\text{+}\text{1}\text{2}$, in agreement with the excitation of the $\text{1}\text{g}\text{1}\text{2}\text{and}\text{2}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ inner- hole strengths in ¹¹¹Sn. In addition a substantial amount of the $\text{2}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ component is observed between 4.5 and 6.0 MeV.The results of the data analysis allow us to clearly eastablish the spreading of the $\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ innerhole strength and to a lesser extent the strong fragmentation of the $\text{2}\text{p}\text{1}\text{2}\text{and}\text{2}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ inner-hole subshells.     

Vector analysing power and cross section for 90Zr(d, p)91Zr at 11 and 12 MeV

Angular distributions of the vector analysing power and the cross section were measured for ⁹⁰Zr($\text{d}$, p)⁹¹Zr. Measurements were made on two transitions at a deuteron energy of 11 MeV and on 20 transitions at 12 MeV. The observed j-dependence of the vector analysing power provided unambiguous spin assignments for most final states. Measurements of the cross section and vector analysing power were also made for deuteron elastic scattering at 11 MeV in order to determine the potential parameters for DWBA calculations. The DWBA predictions are in good agreement with the measured (d, p) cross sections and in qualitative agreement with the analysing powers. Enriched targets.