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Register a new userNeutron-hole states in 45Ar from p(46Ar,d)45Ar reactions
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To improve the effective interactions in the pf shell, it is important to measure the single particle- and hole- states near the N=28 shell gap. In this paper, the neutron spectroscopic factors of hole-states from the unstable neutron-rich 45Ar (Z=18, N=27) nucleus have been studied using 1H(46Ar, 2H)45Ar transfer reaction in inverse kinematics. Comparison of our results with the particle-states of 45Ar produced in 2H(44Ar, H)45Ar reaction shows that the two reactions populate states with different angular momentum. Using the angular distributions, we are able to confirm the spin assignments of four low-lying states of 45Ar. These are the ground state (f7/2), the first-excited (p3/2), the s1/2 and the d3/2 states. While large basis shell model predictions describe spectroscopic properties of the ground and p3/2 states very well, they fail to describe the s1/2 and d3/2 hole-states.
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Spectroscopic information has been extracted on the hole-states of $^{55}$Ni, the least known of the quartet of nuclei ($^{55}$Ni, $^{57}$Ni, $^{55}$Co and $^{57}$Co), one neutron away from $^{56}$Ni, the N=Z=28 double magic nucleus. Using the $^{1}$H($^{56}$Ni,d)$^{55}$Ni transfer reaction in inverse kinematics, neutron spectroscopic factors, spins and parities have been extracted for the f$_{7/2}$, p$_{3/2}$ and the s$_{1/2}$ hole-states of $^{55}$Ni. This new data provides a benchmark for large basis calculations that include nucleonic orbits in both the sd and pf shells. State of the art calculations have been performed to describe the excitation energies and spectroscopic factors of the s$_{1/2}$ hole-state below Fermi energy.
Direct neutron capture reactions play an important role in nuclear astrophysics and applied physics. Since for most unstable short-lived nuclei it is not possible to measure the $(n, gamma)$ cross sections, $(d,p)$ reactions have been used as an alternative indirect tool. We analyze simultaneously $^{48}{rm Ca}(d,p)^{49}{rm Ca}$ at deuteron energies $2, 13, 19$ and 56 MeV and the thermal $(n,gamma)$ reaction at 25 meV. We include results for the ground state and the first excited state of $^{49}$Ca. From the low-energy $(d,p)$ reaction, the neutron asymptotic normalization coefficient (ANC) is determined. Using this ANC, we extract the spectroscopic factor (SF) from the higher energy $(d,p)$ data and the $(n, gamma)$ data. The SF obtained through the 56 MeV $(d,p)$ data are less accurate but consistent with those from the thermal capture. We show that to have a similar dependence on the single particle parameters as in the $(n, gamma)$, the (d,p) reaction should be measured at 30 MeV.
Existing measurements of the angular distributions of the ground-state to ground-state transitions of the 12C(d,p)13C and 13C(p,d)12C neutron-transfer reactions have been analyzed systematically using the Johnson-Soper adiabatic and distorted-wave theories. When using a consistent set of physical inputs the deduced spectroscopic factors are consistent to within 20% for incident deuteron energies from 6 to 60 MeV. By contrast, original analyses of many of these data quoted spectroscopic factors that differed by up to a factor of five. The present analysis provides an important reference point from which to assess the requirements of future spectroscopic analyses of transfer reactions measured in inverse kinematics using rare nuclei.
The bound states of 12Be have been studied through a 11Be(d,p)12Be transfer reaction experiment in inverse kinematics. A 2.8 MeV/u beam of 11Be was produced using the REX-ISOLDE facility at CERN. The outgoing protons were detected with the T-REX silicon detector array. The MINIBALL germanium array was used to detect gamma rays from the excited states in 12Be. The gamma-ray detection enabled a clear identification of the four known bound states in 12Be, and each of the states has been studied individually. Differential cross sections over a large angular range have been extracted. Spectroscopic factors for each of the states have been determined from DWBA calculations and have been compared to previous experimental and theoretical results.
The region around neutron number N = 60 in the neutron-rich Sr and Zr nuclei is one of the most dramatic examples of a ground state shape transition from (near) spherical below N = 60 to strongly deformed shapes in the heavier isotopes. The single-particle structure of 95-97Sr approaching the ground state shape transition at 98 Sr has been investigated via single-neutron transfer reactions using the (d, p) reaction in inverse kinematics. These reactions selectively populate states with a large overlap of the projectile ground state coupled to a neutron in a single-particle orbital. Radioactive 94,95,96Sr nuclei with energies of 5.5 AMeV were used to bombard a CD 2 target. Recoiling light charged particles and {gamma} rays were detected using a quasi-4{pi} silicon strip detector array and a 12 element Ge array. The excitation energy of states populated was reconstructed employing the missing mass method combined with {gamma}-ray tagging and differential cross sections for final states were extracted. A reaction model analysis of the angular distributions allowed for firm spin assignments to be made for the low-lying 352, 556 and 681 keV excited states in 95Sr and a constraint has been placed on the spin of the higher-lying 1666 keV state. Angular distributions have been extracted for 10 states populated in the d(95Sr,p)96Sr reaction, and constraints have been provided for the spins and parities of several final states. Results are compared to shell model calculations in several model spaces and the structure of low-lying states in 94Sr and 95Sr is well-described. The spectroscopic strength of the 0+ and 2 states in 96Sr is significantly more fragmented than predicted.
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