Incident Deuteron Research Articles

A study of the states of 30Si with the 28Si(t, p) 30Si and 29Si(d, p) 30Si reactions

The excitation energies of the levels in 30Si have been measured up to an excitation of 9.46 MeV with the 28Si(t, p) 30Si reaction at a triton energy of 6.0 MeV. Angular distributions have been measured of proton groups from the 28Si(t, p) 30Si and 29Si(d, p) 30Si reactions in a multi-angle magnetic spectrograph. Triton bombarding energies of 10.5 and 12.1 MeV were used and the deuteron incident energy was 10.0 MeV. States in 30Si up to an excitation of 8 MeV were observed. Spins and parities of several states have been assigned using an empirical method for the (t, p) results and using a DWBA analysis for the (d, p) distributions. Spectroscopic factors for twelve states were obtained from the latter analysis. Two of these disagree with theoretical predictions. The state previously reported at an excitation of 6.63 MeV in 30Si was observed to be formed by a strong L = 0 transition in the (t, p) reaction and also by a strong l = 1 transition in the (d, p) reaction. We deduce that there are two closely spaced states at about this excitation, one having a spin and parity of 0 + and the other 0 −, 1 − or 2 −.

Study of the (d, α) reaction applied to 50Cr and 52Cr

The reactions 50Cr(d, α) 48V and 52Cr(d, α) 50V have been carried out at an incident deuteron energy of 15 MeV to investigate the structure of the low-lying levels of 48V and 50V in the light of shell model expectations. Excitation energies and angular distributions have been measured for states up to about 1.5 MeV. For all resolved and strongly excited levels angular momentum transfers could be assigned by comparison with DWBA calculations. For 50V spectroscopic factors have been extracted in relative units assuming pure configurations for the transferred pair of nucleons. The results indicate the existence of seniority and configuration mixing in the level structure of the 48V and 50V isotopes. In both reactions some transitions show characteristic deviations from the direct reaction mechanism. These deviations cannot be reproduced by the DWBA calculations.

Rotational Bands inTm168from theTm169(d,t)Tm168Reaction

The $^{169}\mathrm{Tm}(d,t)^{168}\mathrm{Tm}$ reaction has been studied at an incident deuteron energy of 17.0 MeV. The excitation energies of more than 55 states up to 1.5 MeV in the residual nucleus were obtained to an accuracy of \ifmmode\pm\else\textpm\fi{}0.15%, and the ground-state $Q$ value for the $^{169}\mathrm{Tm}(d,t)^{168}\mathrm{Tm}$ reaction was measured to be ${Q}_{0}=\ensuremath{-}1775\ifmmode\pm\else\textpm\fi{}6$ keV. Differential cross sections were measured at 2.5\ifmmode^\circ\else\textdegree\fi{} intervals from $7.5\ifmmode^\circ\else\textdegree\fi{}\ensuremath{\le}{\ensuremath{\theta}}_{\mathrm{lab}}\ensuremath{\le}45\ifmmode^\circ\else\textdegree\fi{}$, and then at 5\ifmmode^\circ\else\textdegree\fi{} intervals for $45\ifmmode^\circ\else\textdegree\fi{}\ensuremath{\le}{\ensuremath{\theta}}_{\mathrm{lab}}\ensuremath{\le}90\ifmmode^\circ\else\textdegree\fi{}$ for most of these transitions. The resulting angular distributions were found to be well described by distorted-wave calculations for almost all transitions observed. The $l$-transfer values deduced for these transitions allowed the assignment of a narrow range of ${J}^{\ensuremath{\pi}}$ values to the corresponding states in $^{168}\mathrm{Tm}$, independent of arguments based on the Nilsson-model predictions of transition strengths. Several anomalous angular distributions to presumably well-known rotational states which apparently cannot be explained by the distorted-wave calculations are discussed. Spectroscopic factors for all the observed transitions were computed and are compared to the Nilsson-model predictions for low-lying negative-parity bands. Transition-strength anomalies are discussed.

Vector and tensor analysing power of (d, p) reactions and deuteron D-state effects

The vector and tensor analysing power was measured for (d, p) reactions on 9Be, 12C, 16O, 19F, 25Mg, 28Si and 40Ca for lab reaction angles from 0° to 50° at 12.3 MeV incident deuteron energy. Fifteen transitions were studied including orbital angular momentum transfers l n = 0,1,2, 3. The experimental results were analysed in terms of distorted-wave theory including deuteron D-state effects. The calculations show that the deuteron D-state cannot be ignored in the description of the tensor analysing power. The j-dependence of D-state effects is discussed.

A study of the 138Ba(d, p) 139Ba reaction at 19 MeV

The 138Ba(d,p) reaction has been studied at an incident deuteron energy of 19 MeV, using the injector-tandem accelerator and the multichannel magnetic spectrograph of the University of Oxford. Deuteron and proton optical model parameters have been obtained from the analysis of elastic scattering experiments on a 138Ba target. The parameters have been used to calculate theoretical (d, p) angular distributions on the basis of the DWBA. From the comparison of experimental and theoretical distributions, orbital angular momentum transfers have been deduced and spectroscopic factors determined for all the levels observed up to an excitation energy of 2.5 MeV in 139Ba. The spectroscopic information thus obtained is more complete than that from previous studies, and is in satisfactory agreement with expected sum rule limits. A notable item of new information is the assignment of an l n = 6 transition to the level at 1.54 MeV in 139Ba.

Gamma Decay of Excited States inBi210and an Interpretation with the Shell Model

The $\ensuremath{\gamma}$ decay of excited states in $^{210}\mathrm{Bi}$ up to 3250-keV excitation energy has been studied with the $^{209}\mathrm{Bi}(d, p\ensuremath{\gamma})$ reaction at 8.0- and 10.0-MeV incident deuteron energies, using particle-$\ensuremath{\gamma}$ and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidence techniques and a pulsed deuteron beam. For almost all of the states excited in this reaction, $\ensuremath{\gamma}$-decay branching ratios were obtained. The branched decay of states with a dominant configuration (${d}_{\frac{5}{2}}^{\ensuremath{\nu}}\ensuremath{\bigotimes}{h}_{\frac{9}{2}}^{\ensuremath{\pi}}$) into states with a (${g}_{\frac{9}{2}}^{\ensuremath{\nu}}\ensuremath{\bigotimes}{h}_{\frac{9}{2}}^{\ensuremath{\pi}}$) configuration was analyzed to determine experimentally the amount of configuration mixing between these two multiplets. The obtained mixing amplitudes are in remarkably good agreement with shellmodel calculations. From the observed lifetimes of the ${({g}_{\frac{9}{2}}^{\ensuremath{\nu}}\ensuremath{\bigotimes}{h}_{\frac{9}{2}}^{\ensuremath{\pi}})}_{{5}^{\ensuremath{-}},{7}^{\ensuremath{-}}}$ states, a reduced matrix element of $〈{g}_{\frac{9}{2}}^{\ensuremath{\nu}}\ensuremath{\parallel}E2\ensuremath{\parallel}{g}_{\frac{9}{2}}^{\ensuremath{\nu}}〉=\ensuremath{-}38\ifmmode\pm\else\textpm\fi{}4 e$ ${\mathrm{fm}}^{2}$ has been extracted. This value is in good agreement with an intermediate coupling calculation which yields $\ensuremath{-}35 e$ ${\mathrm{fm}}^{2}$.

Observation of the ABC effect in the reaction d + d → α + (mm) 0

The reaction d + d → α + (mm) 0 where he missing mass sytem is in a pure state of isospin I = 0, is studied using 2.49 GeV/ c incident deuterons and the missing mass technique. The ABC effect is observed, dominating the missing mass spectrum with a production cross section of 0.66 μb/sr at zero degrees in the center of mass system.

The 144Nd(d, p) and 144Nd(d, t) reactions and isobaric analog resonances in 144Nd(p, p 0) and 144Nd(p, p')

The reactions 144Nd(d, p) and 144Nd(d, t), at an incident deuteron energy of 12.6 MeV, have been investigated with an energy resolution of about 16 keV, and excitation functions for the reactions 144Nd(p, p 0) and 144Nd(p, p') have been measured from 9.3 to 12 MeV incident proton energies. The analysis of the analog resonances observed in the excitation functions is compared with the results of the 144Nd(d, p) experiment.

Pauli Exclusion Effects in Reactions Involving Multinucleon Systems

To investigate the importance of effects of Pauli exclusion principle in reactions involving multinucleon systems, we consider reactions in which deuterons are incident on a recoilless nucleus. First, the binding energy of a model deuteron in the presence of a nuclear Fermi gas (an infinite nucleus) is calculated as a function of nuclear density and deuteron kinetic energy so as to provide some clues to the range of incident energies and nuclear densities where exclusion effects can be expected to be important. The results show that this model deuteron is unbound in the presence of infinite nuclear matter, unless it has a kinetic energy, at least, of the order of 100 MeV. Making some simplifying assumptions, then, we pose a model problem and obtain for the deuteron breakup, elastic scattering, and stripping reactions, Hilbert-Schmidt integral equations in which the Pauli term, in each case, can be identified. Corresponding to Pauli breakup term, Pauli breakup cross sections for deuterons on $^{16}\mathrm{O}$ nucleus have been calculated in a simple model. The dependence of cross sections on directions along which the breakup products emerge and the energy partition among them is investigated. The variation of cross section with incident deuterons' kinetic energy and with nuclear density is also studied. The most prominent and important feature of Pauli breakup is the sharp peaking of cross sections for very asymmetric partition of energy among outgoing particles and is very encouraging for an experimental test. Finally, by considering Pauli breakup of an artifically tightly bound deuteron, we conclude that the Pauli mechanism should be of importance in $\ensuremath{\alpha}$-particle reactions as well.

Comparison of sub-coulomb stripping and analog resonance results in 93Zr

The 92Zr(d, p) 93Zr reaction, leading to states in 93Zr which are parents of analog states observed in 92Zr(p, p) elastic scattering, has been studied for incident deuteron energies below the Coulomb barrier. For each of the parent states the reduced normalization has been extracted, and these have been compared with the reduced normalizations calculated for the analog resonances on the basis of various analog resonance theories.

Analysis of the 48Ca(d, p) 49Ca reaction for incident energies below and above the Coulomb barrier

The 48Ca(d,p) 49Ca reaction has been studied at incident deuteron energies of 1.992, 2.485 and 2.925 MeV. Angular distributions for the ground state (2 p 3 2 ) and first excited state (2 p 1 2 ) were obtained at lab angles between 7.5° and 172.5°. Distorted-wave Born calculations were carried out using several sets of parameters, both in the zero-range local approximation and also introducing finite-range and non-local corrections. Those calculations were extended up to 7.2 MeV bombarding energy to include data taken previously at this laboratory.

Coulomb (d, p) stripping to states in 117,123,125Sn

Angular distributions were measured for the reactions 116Sn(d, p) 117Sn(d, p) 123Sn and 124Sn(d, p) 125Sn at several incident deuteron energies between 4.55 and 5.55 MeV. Below 5.2 MeV excitation energy, 52 levels are observed in 117Sn, 49 in 123Sn, and 49 in 125Sn. Many of the upper levels in all three nuclei are previously unreported, as is the 0.859 MeV level in 125Sn. Spectroscopic factors and reduced widths for many states of interest were extracted using the DWBA theory. Comparison with Spectroscopic factors from other experiments and with results from pairing theory calculations reveals general agreement, although not within the accuracy expected for the present results.

Level structure of 28Al

The energy-level structure of 28Al has been studied by the 27Al(d, p) reaction with 6.0 MeV incident deuterons. Thirty-six energy levels up to 5.13 MeV were analyzed. The angular distributions for the observed transitions are compared with distorted-wave Born approximation calculations. Angular momentum transfers are determined and spectroscopic strengths are deduced from the data. The results are compared with shell-model sum rules.

Polarization of protons from the 9Be(d, p)10Be reaction at Ed = 12.0 MeV

Abstract The polarization of protons from the 9 Be(d,p) 10 Be reaction at E d = 12.0 MeV was measured for the ground state and first excited state transitions. The results obtained are compared with the predictions of DWBA theory. It was found that better fits to the experimental data can be obtained using volume absorption in the distorting potential of the deuteron elastic channel. A comparison of the present polarization data with the vector analysing power for the same reaction and the same incident deuteron energy has also been made.

The energy levels of 21Na

The energy levels of 21Na are investigated with the 20Ne(p, γ) 21Na and 20Ne(d, n) 21 Na reactions. From the γ-ray energy measurements the excitation energies in 21Na are found to be 331 ± 3, 1717 ± 3, 2426 ± 2, 2800 ± 4, 3545 ± 3, 3679 ± 4, 3867 ± 4, 4117 ± 11 and 4297 ± 4 keV. A 20Ne(p, γ) 21Na Q-value of 2434 ± 2 keV is deduced. Branching ratios are determined for the upper five levels. Direct non-resonant capture is observed to the 0.33 and 2.43 MeV states. Angular distributions for the 20Ne(d, n) 21Na reaction are presented for all of these levels and for levels at 4453 ± 12 keV and 5009 ± 12 keV for incident deuteron energies of 3.60, 4.88, 5.57 and 5.94 MeV. The unbound 4.12 MeV state has a stripping pattern consistent with l = 1. Its lab width from the γ-ray work is 125 keV. The combined evidence of the branching ratios, reduced widths and stripping patterns show that the 4.12 keV level is the mirror of the 4.73 MeV level in 21Ne.

Four-nucleon studies: (II). Determination of the [formula omitted] neutron polarization using a 16 to 22 MeV pulsed deuteron beam from the cyclograaff

The neutron polarization from the 2 H( d, n ) 3 He reaction has been measured at 45° c.m. for incident deuteron energies between 16 and 22 MeV. In addition, a polarization angular distribution was measured at 18 MeV. The results show that the 45° c.m. polarization remains above 0.35 in this energy range, but the peak polarization has shifted to near 40° c.m. The usefulness of 2 H( d, n ) as a source of 10 to 22 MeV polarized neutrons is discussed.

A fast neutron spectrometer and its use in determining the energy spectra of some cyclotron-produced fast neutron beams.

Abstract This paper describes the development of a fast neutron spectrometer and its application to the measurement of the fast neutron spectrum of the beam produced by the Medical Research Council (MRC) Cyclotron. In addition, spectra produced by bombarding thin beryllium targets and a thick carbon target with 16 MeV deuterons have been determined. Spectra of beams produced by bombarding thick targets of beryllium and heavy water with 16 and 11 MeV deuterons have been reported previously (Parnell, Page, and Chaudhri, 1971). The fast neutron beam produced by the M.R.C. Cyclotron results from the bombardment of a beryllium target with 16·7 MeV deuterons. The thickness of the beryllium is nominally 0·8 mm and is not sufficient to stop the incident deuterons completely. Instead, they are brought to rest in the copper backing on which the beryllium is mounted (Parnell, 1971). The energy spectrum published previously for this beam (Bewley, 1963) requires modification. At that time a thick beryllium target was ...

The 57Fe(d, p) 58Fe reaction and the structure of 58Fe

The level structure of 58Fe has been studied by the 57Fe(d, p) reaction with 7.0 MeV incident deuterons, using the MIT multiple-angle spectrograph. Experimental angular distributions are compared with distorted-wave Born approximation calculations. Angular momentum values are determined for the observed transitions up to approximately 6.0 MeV excitation energy. Spectroscopic strengths are deduced from the data. The results are analyzed in terms of shell-model sum rules.

An associated particle neutron time of flight system

A fast 3Hen timing system having significantly improved timing resolution has been developed for the D(d, n) 3He reaction at incident deuteron energies below 400 keV. The associated particle technique is used to define a neutron beam at an angle in the laboratory between 40° and 120°, determined by the angle at which the associated 3He particles are detected. Unambiguous 3He particle detection, resulting from the use of a magnetic analyser to shield the surface barrier 3He particle detector from scattered deuterons, allows the absolute neutron flux in the associated neutron beam to be precisely determined. The derivation of a fast timing signal from the detector voltage pulse, enables a constant fraction pulse height discriminator to be triggered on 3He pulses of equivalent energy less than 500 keV without spurious triggering on noise. The 3He-n timing resolution obtained after compensation for the energy dependent 3He flight times is 2.8 ns (fwhm) in the particular case of a 2.40 MeV neutron beam defined at 102°, and 3.2 ns (fwhm) in the case of a 2.80 MeV neutron beam at 50°. The effect of instrumental timing jitter and walk in the system is virtually negligible. Stable neutron beams having intensities of over 120 neutrons sec −1 msterad −1 averaged over the beam profile are maintained for long periods. The random background count rates outside the neutron beam typically correspond to a neutron flux of less than 2 × 10 −5 that of the direct beam.

Coulomb stripping in 58,62,64Ni(d, p)59,63,65Ni

The 58,62,64Ni(d, p) stripping reactions have been studied up to a high excitation energy at an incident deuteron energy of Ed = 2.9MeV. The spectroscopic factors (2J+1)S for some excited states differ from those measured at an incident deuteron energy above the Coulomb barrier. For high excited states these anomalies can be explained by the wrong assignment of ln in previous investigations. For low-lying levels of the residual nuclei, the proton energy exceeds the Coulomb barrier and the anomalies observed are apparently due to multistep stripping.