Search

A High Rigidity Spectrometer (HRS) has been designed for experiments at the Facility for Rare-Isotope Beams (FRIB) at Michigan State University (MSU). The HRS will allow experiments to be performed with the most exotic neutron-rich isotopes at high beam energies ($\gtrsim$100MeV/u). The HRS consists of an analysis beamline called the High-Transmission Beamline (HTBL) and the spectrometer proper called the Spectrometer Section. The maximum magnetic rigidity of the HRS is 8Tm, which corresponds to the rigidities at which rare-isotope beams are optimally produced at FRIB. The resolving power, angular acceptance, and momentum acceptance are set to match the anticipated scientific program. An ion-optical design developed for the HRS is described in detail, along with the specifications of the associated magnet and detector systems., Comment: 24 pages, 26 figures, 6 tables

Y. Fujita1,2 H. Fujita1 T. Adachi1 C.L. Bai3 A. Algora4,5 G.P.A. Berg6 P. von Brentano7 G. Colo8 M. Csatlos5 J.M. Deaven9 E. Estevez-Aguado4 C. Fransen7 D. De Frenne10 K. Fujita1 E. Ganioglu11 C.J. Guess9 J. Gulyas5 K. Hatanaka1 K. Hirota1 M. Honma12 D. Ishikawa1 E. Jacobs10 A. Krasznahorkay5 H. Matsubara1 K. Matsuyanagi13 R. Meharchand9 F. Molina4 K. Muto14 K. Nakanishi1 A. Negret15 H. Okamura1 H.J. Ong1 T. Otsuka16 N. Pietralla7 G. Perdikakis9 L. Popescu17 B. Rubio4 H. Sagawa13 P. Sarriguren18 C. Scholl7 Y. Shimbara19 Y. Shimizu1 G. Susoy11 T. Suzuki1 Y. Tameshige1 A. Tamii1 J.H. Thies20 M. Uchida1 T. Wakasa1 M. Yosoi1 R.G.T. Zegers1 K.O. Zell7 J. Zenihiro1

The TRI mu P facility, under construction at KVI, requires the production and separation of short-lived and rare isotopes. Direct reactions, fragmentation and fusion-evaporation reactions in normal and inverse kinematics are foreseen to produce nuclides of interest with a variety of heavy-ion beams from the superconducting cyclotron AGOR. For this purpose, we have designed, constructed and commissioned a versatile magnetic separator that allows efficient injection into an ion catcher, i.e., gas-filled stopper/cooler or thermal ionizer, from which a low energy radioactive beam will be extracted. The separator performance was tested with the production and clean separation of Na-21 ions, where a beam purity of 99.5% could be achieved. For fusion-evaporation products, some of the features of its operation as a gas-filled recoil separator were tested. (c) 2006 Elsevier B.V. All rights reserved.

The cross section of the O16(p,p′)O16(0−,T=1) scattering was measured at a bombarding energy of 295 MeV in the momentum transfer range of 1.0fm−1⩽qc.m.⩽2.1fm−1. The isovector 0− state at Ex=12.8MeV is clearly separated from its neighboring states owing to the high energy resolution of about 30 keV. The cross section data were compared with distorted wave impulse approximation (DWIA) calculations employing shell-model wave functions. The observed cross sections around qc.m.≃1.7fm−1 are significantly larger than obtained by these calculations, suggesting pionic enhancement as a precursor of pion condensation in nuclei. The data are well reproduced by DWIA calculations using random phase approximation response functions including the Δ isobar that predict pionic enhancement.

Under the assumption that isospin is a good quantum number, symmetry is expected for the transitions from the ground states of T = 1, T z = ±1 nuclei to the common excited states of the T z = 0 nucleus situated between the two nuclei. The symmetry can be studied by comparing the strengths of Gamow-Teller (GT) transitions obtained from a (p, n)-type charge-exchange reaction on a target nucleus with T z = 1 with those from the β-decay of the T z = - 1 nucleus. The A = 58 system is the heaviest for which such a comparison is possible. As a part of the symmetry study, we measured the GT transitions from 58Ni (T z = 1) to 58Cu (T z = 0) by using the zero-degree (3 He, t) reaction at 150 MeV/nucleon. With the achieved resolution of 50 keV, many hitherto unresolved GT states have been identified. The GT transition strengths were obtained for states up to 8 MeV excitation, i.e., near to the Q window limitation ( Q EC = 9.37 MeV) of the β-decay from 58Zn (T z = - 1) to 58Cu. The strength distribution is compared with that from shell-model calculations.

The ( α , 8 He) reaction is used to measure level energies in very proton rich nuclei. The results allow a more reliable calculation of the reaction flow in the rp and αp processes in Novae, X-ray pulsars and X-ray bursts.

The (7Li,7Be) and (7Li,7Beγ) reactions have been studied at bombarding energies of 50 A MeV on targets of 6Li, 12C, 90Zr, 120Sn, 208Pb, and polystyrene. The detection of Doppler-shifted γ-rays from excited 7Be permits the identification of the spinflip and non-spinflip characteristics. Transitions to over 20 discrete states and resonances have been observed. Angular distributions for 6Li and 12C are well described by microscopic one-step distorted-waves calculations with shell-model transition amplitudes. The transitions to the ground states of 6He and 12C exhibit significant Gamow-Teller strength, but ∼7% and ∼17%, respectively, of the calculated cross sections at θ ≈ 0° arise from the tensor interaction. A broad resonance at ∼5.6 MeV in the halo nucleus 6He with Jπ = (2+,1−,0+) seems to correspond to a structure predicted at this excitation energy containing soft modes of excitation with Jπ = 0+and/or 2+. A resonance in 12B at ∼4.5 MeV is described by a superposition of known 2− and 4− states, and another one at ∼7.5 MeV is dominated by a transition to a 2− state with weaker contributions from two 1− states (spin dipole and giant dipole). Four to six resonances each, mostly spin-dipole resonances, were identified in the final nuclei 90Y, 120In, and 208Tl. The non-resonant quasi-free charge-exchange reaction pbound(7Li,7Be)nfree was observed for all targets up to effective excitation energies of 50 MeV. The mechanism is related to that on free protons. The effective number of participating protons was determined.

The position of the K 17 2 shell orbital plays a significant role in determining the shell correction energy and hence the stability of the superheavy elements. A deformed component of this orbital, 1 2 + [880] , comes down in energy with increasing prolate deformation, and is expected to have an excitation energy of less than 2 MeV in nuclei with N = 153. We have performed the reaction 248Cm(4He,3He) using 98.5-MeV alpha particles from the IUCF cyclotron to populate high-l states in 249Cm. this reaction preferentially excites high-l states because of the angular momentum mismatch. The emerging 3He ions were momentum analyzed with the K600 magnetic spectrometer. Spectra were measured at θcm = 4.1°, 6.1°, 10.2°, 12.2°, and 16.2° The spectrometer was calibrated with the 208Pb(4He,3He) and 232Th(4He,3He) reactions at the same incident energy. Three strong peaks were identified in the 248Cm(4He,3He) spectrum and these have been given tentative assignments: 593 keV, 15 2 11 2 − [725] ; 1560 keV and 1898 keV, 17 2 1 2 + [880] , 15 2 13 2 − [716] . Our data do not distinguish between the 17 2 + and 15 2 − assignments.

Zero-degree cross sections have been measured for (t, 3 He) reactions on the light target nuclei 9 Be, 10 B, 11 B, 12 C, and 13 C at a bombarding energy of 127 MeV/A. The triton beam was produced by ( 4 He,t+p) breakup on a Be production target using a 4 He beam of 155 MeV/A. Dispersion matching was applied to obtain good energy resolution ( Δ E/E=0.002, Δ E=780 keV). The zero-degree (t, 3 He) cross sections are used to discuss Gamow-Teller strengths in 10 Be and 11 Be.

Initial experiments were carried out to study spin-isospin transitions in nuclei using (t,3He) measurements. A triton beam was produced from the breakup reaction (4He,t-p) on a 9.25 g/cm2 Be production target using a 4He beam of 620 MeV. With a beam of 70 enA a yield of 381 MeV tritons with 4.5 × 106 particles/s was achieved. The first half of the A1200 beam transport system at NSCL was used to analyze the triton beam. The energy spread at the target position was estimated to be about 23 MeV. The second half of the A1200 was used to analyze the energy of 3He particles from the (t,3He) reaction. The dispersion matching method was applied to obtain good energy resolution despite the significant energy spread of the incident tritons. The achromatic properties of the A1200 system made it possible to obtain high-resolution (t,3He) spectra at θ = 0° with a resolution of ΔEE = 0.002 (ΔE = 780 keV).

The isoscalar giant dipole resonance (ISGDR) in ${}^{208}\mathrm{Pb}$ has been investigated using inelastic scattering of 200 MeV $\ensuremath{\alpha}$ particles at and near 0\ifmmode^\circ\else\textdegree\fi{} where the angular distribution of the ISGDR can be clearly differentiated from those of other modes. The ``difference of spectra'' technique was employed to separate the ISGDR from the high-energy octupole resonance (HEOR). These data provide the clearest evidence yet for the ISGDR adjacent to the HEOR. With these results, all expected isoscalar $\ensuremath{\lambda}\ensuremath{\le}3$ resonances in ${}^{208}\mathrm{Pb}$ have been identified.

We used the $^{16}\mathrm{O}$${(}^{3}$He,n${)}^{18}$Ne, $^{12}\mathrm{C}$${(}^{12}$C${,}^{6}$He${)}^{18}$Ne, and $^{20}\mathrm{Ne}$(p,t${)}^{18}$Ne reactions to study $^{18}\mathrm{Ne}$ states up to an excitation energy of 10 MeV, with emphasis on levels corresponding to $^{14}\mathrm{O}$(\ensuremath{\alpha},p${)}^{17}$F and $^{17}\mathrm{F}$(p,\ensuremath{\gamma}${)}^{18}$Ne resonances that could strongly affect these reaction rates in hot stellar environments. Excitation energies, widths, absolute cross sections, and angular distributions were measured. We found previously unidentified states at ${\mathit{E}}_{\mathit{x}}$=6.15\ifmmode\pm\else\textpm\fi{}0.01 MeV, 7.12\ifmmode\pm\else\textpm\fi{}0.02 MeV, 7.35\ifmmode\pm\else\textpm\fi{}0.02 MeV, 7.62\ifmmode\pm\else\textpm\fi{}0.02 MeV, 8.30\ifmmode\pm\else\textpm\fi{}0.02 MeV, (8.45\ifmmode\pm\else\textpm\fi{}0.03 MeV), 8.55\ifmmode\pm\else\textpm\fi{}0.03 MeV, 8.94\ifmmode\pm\else\textpm\fi{}0.02 MeV, and 9.58\ifmmode\pm\else\textpm\fi{}0.02 MeV. We combined level width, cross section, and angular distribution data to infer ${\mathit{J}}^{\mathrm{\ensuremath{\pi}}}$ values for a number of the new levels as well as for the previously known 5.1-MeV doublet. Using information from our experiments, we recalculated the $^{14}\mathrm{O}$(\ensuremath{\alpha},p${)}^{17}$F reaction rate, which constitutes a possible path out of the hot CNO cycle into the rp process and could play an important role in transforming nuclei involved in the hot CNO cycle into heavier nuclei with Z\ensuremath{\ge}10. \textcopyright{} 1996 The American Physical Society.

The $^{6}\mathrm{Li}$${(}^{7}$Li${,}^{7}$Be${)}^{6}$He charge-exchange reaction leading to the neutron-halo nucleus $^{6}\mathrm{He}$ has been studied at E${(}^{7}$Li) = 350 MeV. Magnetic analysis was used to observe transitions to the known ${\mathit{J}}^{\mathrm{\ensuremath{\pi}}}$ = ${0}^{+}$ ground state and the ${\mathit{J}}^{\mathrm{\ensuremath{\pi}}}$ = ${2}^{+}$ state at ${\mathit{E}}_{\mathit{x}}$ = 1.8 MeV as well as pronounced resonances at \ensuremath{\sim}5.6 MeV, \ensuremath{\sim}14.6 MeV, and \ensuremath{\sim}23.3 MeV. Coincidences with 430-keV Doppler-shifted \ensuremath{\gamma} rays from the deexcitation in flight of the ${\mathit{J}}^{\mathrm{\ensuremath{\pi}}}$ = 1/${2}^{\mathrm{\ensuremath{-}}}$ first-excited state in $^{7}\mathrm{Be}$ were measured to permit the identification of spin-flip transitions. All observed transitions appear to have spin-flip characteristics. The shapes of the experimental angular distributions from ${\mathrm{\ensuremath{\theta}}}_{\mathrm{c}.\mathrm{m}.}$ = 0\ifmmode^\circ\else\textdegree\fi{} to 18\ifmmode^\circ\else\textdegree\fi{} are well described by microscopic one-step finite-range distorted-wave calculations with theoretical shell-model transition amplitudes. For the two low-lying shell-model states the absolute cross sections are also well described. The internal structures of the projectile and ejectile are taken into consideration. A large number of contributions is permitted by the angular momentum couplings. Only the ground state of $^{6}\mathrm{He}$ carries significant Gamow-Teller strength B(GT). Contributions with higher L values from the central spin flip and the tensor interactions ${\mathit{V}}_{\mathrm{\ensuremath{\sigma}}\mathrm{\ensuremath{\tau}}}$ and ${\mathit{V}}_{\mathit{T}\mathrm{\ensuremath{\tau}}}$ are responsible for the mostly structureless distributions observed, and the 0\ifmmode^\circ\else\textdegree\fi{} cross sections are not proportional to B(GT). The strong resonances at \ensuremath{\sim}5.6 MeV and \ensuremath{\sim}14.6 MeV are interpreted as ${2}^{+}$ and (1,2${)}^{\mathrm{\ensuremath{-}}}$ resonances, respectively, with cross sections stronger than predicted presumably due to mixing with continuum states leading to quadrupole and dipole enhancements. It appears that the resonance at \ensuremath{\sim}5.6 MeV does not represent a soft dipole mode originally predicted at ${\mathit{E}}_{\mathit{x}}$=4--7 MeV. \textcopyright{} 1996 The American Physical Society.

The (7Li,7Be) charge-exchange reaction has been studied at E( 7 Li)=350 MeV on targets of 6Li, 12C, 90Zr, 120Sn, and 208Pb. Coincidences with Doppler-shifted γ-rays from the de-excitation in flight of the first-excited state in 7Be were recorded to identify spinflip transitions. Numerous discrete states and giant resonances were observed. Angular distributions were obtained for 6Li and 12C targets. They are well described by microscopic finite-range distorted-waves calculations with theoretical shell-model transition amplitudes and a nucleon-nucleon interaction containing central and tensor components.

The isoscalar giant dipole resonance (ISGDR) in 208 Pb has been investigated using inelastic scattering of 200 MeV α particles at and near 0° where the angular distribution of the ISGDR can be clearly differentiated from other modes. The “difference of spectra” technique was employed to separate the contribution from the high-energy octupole resonance (HEOR). Preliminary angular distribution data provide clear evidence for the ISGDR adjacent to the HEOR.

We have made simultaneous measurements of singles ($\stackrel{\ensuremath{\rightarrow}}{p}, {\stackrel{\ensuremath{\rightarrow}}{p}}^{\ensuremath{'}}$) spin-transfer observables and coincident ($\stackrel{\ensuremath{\rightarrow}}{p}, {p}^{\ensuremath{'}}\ensuremath{\gamma}$) yields and asymmetries for the 15.11 MeV, ${1}^{+}$, $T=1$ state in $^{12}\mathrm{C}$, at an incident proton bombarding energy of 200 MeV. Data were taken at four proton scattering angles ranging from ${\ensuremath{\theta}}_{p}^{\mathrm{c}.\mathrm{m}.}=5.5\ifmmode^\circ\else\textdegree\fi{} \mathrm{to} 16.5\ifmmode^\circ\else\textdegree\fi{}$. Both vertical (normal to the reaction plane) and horizontal (in-plane) incident beam polarizations were used, which allowed us to extract 16 different observables for this transition. In particular, using the ($\stackrel{\ensuremath{\rightarrow}}{p}, {p}^{\ensuremath{'}}\ensuremath{\gamma}$) reaction, we measured the sideways and longitudinal analyzing powers, ${D}_{0S}$ and ${D}_{0L}$, which vanish identically in the ($\stackrel{\ensuremath{\rightarrow}}{p}, {p}^{\ensuremath{'}}$) reaction. Detailed comparisons of all observables to calculations done in both relativistic and nonrelativistic formalisms are presented. Surprisingly, a relativistic description in which knock-on exchange processes are not explicitly included provides the best overall agreement with the data.

Fragmentation and splitting of the Gamow-Teller (GT) strength has been observed in a systematic study of the ${(}^{3}$He,t) charge-exchange reaction at E${(}^{3}$He)=200 MeV over the entire range of stable Sn isotopes. Triton energy spectra were observed with a high-resolution magnetic spectrometer at angles near \ensuremath{\theta}=0\ifmmode^\circ\else\textdegree\fi{} where \ensuremath{\Delta}L=0 transitions are enhanced. Excitation energies, widths, 0\ifmmode^\circ\else\textdegree\fi{} cross sections, and strengths B(GT) were determined. A theoretically predicted configuration splitting of the main Gamow-Teller component into two components, expected to be dominant near A=118 at the onset of the filling of the 1${\mathit{h}}_{11/2}$ neutron orbital, could not be observed. This may be due to the fact that the total widths of the resonances of 5--6 MeV exceed the predicted splitting. A comparison of the 0\ifmmode^\circ\else\textdegree\fi{} cross sections for the transitions to the Gamow-Teller resonances and the isobaric analog states leads to strengths B(GT) for the main Gamow-Teller components of typically 65% of the sum-rule value of 3(N-Z). Three to four additional Gamow-Teller fragments (``pygmy resonances'') were observed in all final nuclei at lower excitation energies. The excellent energy resolution of the experiment made it possible to observe a pronounced fine structure in these low-lying resonances which is believed to be due to coupling to two-particle--two-hole doorway states. Also seen with all target nuclei was a systematic sequence of strong ${\mathit{J}}^{\mathrm{\ensuremath{\pi}}}$=${1}^{+}$ states near the ground states in all Sb isotopes (${\mathit{E}}_{\mathit{x}}$=0 to 220 keV). In addition, strong \ensuremath{\Delta}L=1 resonances were observed in all nuclei at excitation energies of typically 20 MeV. Furthermore, nonresonant background from quasifree charge exchange was observed. An average of \ensuremath{\sim}85% of all excess neutrons seems to contribute to this background in approximate agreement with results from (e,e'p) experiments.

The ( 7 Li, 7 Be) nuclear charge-exchange reaction has been investigated at E( 7 Li ) = 350 MeV . Coincidences were measured between the charged 7 Be reaction products in the focal plane of a magnetic spectrometer and 430-keV Doppler-shifted γ-rays from the decay in flight of excited 7 Be ejectiles. The latter were detected in a compact BGO detector array. Fast timing was used to optimize the separation between prompt and randoms events. The BGO output signals display the statistical distribution of the arrival times of individual photoelectrons from the photocathode in the photomultiplier tubes. A timing resolution of 6.5 ns relative to the accelerator RF was obtained. A simple model was successfully developed to simulate the BGO output signals with a statistical distribution of a predetermined number of photoelectrons modulated by the light output response of the scintillator and the single-photoelectron gain distribution and transit time through the photomultiplier tube. It is concluded that the timing resolution is primarily limited by the small number of photoelectrons.

Equilibrium charge-state distributions for singly and doubly ionized [sup 3]He ions of energy [ital E]([sup 3]He)=200 MeV ([beta]=0.36) have been measured for atomic targets ranging from carbon to bismuth ([ital Z]=6,14,28,40,50,67,73,83). A magnetic spectrometer was used to simultaneously measure the rate of [sup 3]He[sup +] ions and the current of the incident beam of [sup 3]He[sup 2+] ions. The ratio of the fraction of ions [ital Y]([sup 3]He)[sup +]/[ital Y]([sup 3]He[sup 2+]) was found to increase from 3[times]10[sup [minus]9] for [ital Z]=6 to 2[times]10[sup [minus]7] for [ital Z]=83. Very good agreement with the experimental ratios was obtained for calculated ratios based on theoretical stripping (ionization) and capture cross sections. The cross sections are dominated by capture from [ital K] orbits only for atoms up to about [ital Z]=25. For target atoms with high [ital Z], contributions up to principal quantum numbers [ital n]=4 ([ital N] orbits) must be included.

In parallel experiments angular distributions of the differential cross sections and vector analyzing powers have been measured for the (d\ensuremath{\rightarrow}${,}^{3}$He) reactions on $^{204}\mathrm{Hg}$ and $^{206}\mathrm{Pb}$ at an incident deuteron energy of 79.1 MeV. The Q values for the reaction on $^{204}\mathrm{Hg}$ and a $^{202}\mathrm{Hg}$ contaminant were determined as -3340.9(3.4) keV and -2738.8(3.5) keV, respectively. Spectroscopic factors on $^{204}\mathrm{Hg}$ and $^{206}\mathrm{Pb}$ were obtained through a consistent distorted wave Born approximation (DWBA) analysis. A combined evaluation of relative spectroscopic factors and electron scattering (CERES) yields 3s-proton occupancies in $^{204}\mathrm{Hg}$ and $^{206}\mathrm{Pb}$. The latter is compatible with an earlier CERES result based on the more accurately known $^{206}--^{205}$Tl charge density difference. Substantial deviations from shell-model occupancies are observed.

The isoscalar giant dipole resonance (ISGDR) in 208Pb has been investigated using inelastic scattering of 200 MeV α particles at and near 0° where the angular distribution of the ISGDR can be clearly differentiated from other modes. The “difference of spectra” technique was employed to separate the contribution from the high-energy octupole resonance (HEOR). Results from a preliminary analysis of the data are consistent with the expected positions of the ISGOR and HEOR, as well as their expected angular distributions near 0°.

Differential cross sections and analyzing powers for scattering of 200 MeV protons have been measured for states of $^{16}\mathrm{O}$ up to 14.4 MeV and for states of $^{40}\mathrm{Ca}$ up to 7.2 MeV of excitation. The data cover c.m. momentum transfers from approximately 0.4 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$ to 3.0 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$. Calculations were performed using several density-dependent effective interactions in the local density approximation. Empirical effective interactions from isoscalar normal-parity transitions were fitted to elastic and inelastic scattering data for $^{16}\mathrm{O}$ and $^{40}\mathrm{Ca}$ either individually or simultaneously. Transition densities from electron scattering were used to minimize uncertainties due to nuclear structure. The fitted interactions were iterated to generate optical potentials self-consistently. We find that the empirical interaction, although strongly dependent on the local density, is essentially independent of target or state. We also find that the empirical interaction is reduced in strength at zero density. Finally, the results were compared with a relativistic impulse approximation model and with a recent global optical potential from Dirac phenomenology.

From the diverse and extensive experimental data on the low-lying structure of the 143 60 Nd 83 nucleus, evidence is gathered for the existence of two-pairing-phonon configurations. Comparison of two-neutron pick-up data 145 Nd(p,t) 143 Nd and gamma-ray data from the reaction 140 Ce(α,nγ) 143 Nd with other experimental data allows one to identify the states at 3040 and 3071 keV as sharing the neutron-pairing vibration excitation ν(1, 1)ν f 7 2 and the state at 2035 keV as being the proton excitation 0 2 + ν f 7 2 . They are the only configurations of this type hitherto known in odd nuclei. The coupling between neutron- and proton-pairing vibrations and the coupling to other excitation modes are discussed.

The (He-3, t) charge-exchange reaction has been studied at theta = 0-degree-C and bombarding energies of E(He-3) = 76.5 MeV and 200 MeV. Spectra were measured using magnetic analysis for target nuclei of C-12, C-13, O-16, F-19, Si-28, Si-29, Si-30, Zr-90, Sn-117, Sn-120, (nat)Ta, (nat)W, Au-197, Pb-208, Th-230, Th-232, U-234, U-236, U-238 and Pu-244. The measurements at 76.5 MeV concentrated on the isobaric analog states of several actinide nuclei, particularly on their widths and the branching ratios for proton decay. Cross sections, Q-values and total widths were determined for the transitions to the isobaric analog states. Coulomb displacement energies derived from the measured Q-values display the influence of deformed nuclear shapes. Escape widths GAMMA-up and spreding widths GAMMA-down of the isobaric analog states in five actinide nuclei were deduced from the measured proton-decay branching ratios. They were found to be in agreement with predictions which postulate isospin mixing via the Coulomb force with the (T0-1)-component of the isovector giant monopole resonance. The measurements at 200 MeV were concerned with transitions to isobaric analog states in both light and heavy nuclei, including several actinide nuclei, but Gamow-Teller resonances and transitions to numerous other states were also observed. The measured cross sections for several transitions to isobaric analog states from Si-30 to Pb-208 were used to extract the effective interaction V(tau) for non-spin-flip (He-3, t) charge exchange at E(He-3) almost-equal-to 200 MeV. The interaction strength V(tau) decreases by a factor 0.6 when compared to previously measured values for the energy range E(He-3) = 65 to 90 MeV. An angular distribution from theta(t) = 0-degree to 16-degrees for the transition to the isobaric analog state in Sb-120 measured at E(He-3) = 200 MeV was found to be in very good agreement with microscopic calculations.

Differential cross sections and analyzing powers were measured for $^{17}\mathrm{O}$(d\ensuremath{\rightarrow},t${)}^{16}$O with polarized deuterons of 89 MeV. States of $^{16}\mathrm{O}$ up to 22.89 MeV excitation energy have been studied with an overall resolution of 60 keV. Discrimination between analyzing powers (${\mathit{A}}_{\mathit{y}}$) for different j transfers was found to be very good. The unique ${\mathit{A}}_{\mathit{y}}$(\ensuremath{\theta}) shapes were used to deduce ${\mathit{p}}_{1/2}$-${\mathit{p}}_{3/2}$ mixing ratios for those levels where it was significant. We find unexpectedly strong mixing for the 6.130 MeV, ${3}^{\mathrm{\ensuremath{-}}}$, and 8.872 MeV, ${2}^{\mathrm{\ensuremath{-}}}$, levels. Exact finite-range distorted-wave Born approximation calculations were used to identify l transfers and to extract spectroscopic strengths. Up to 23 MeV excitation, pickup strength is dominated by 1p transfer; less than 2% of the observed particle-hole strength results from 2s, 1d, or 1f transfer. Twelve particle-hole matrix elements for (${\mathit{p}}_{1/2}^{\mathrm{\ensuremath{-}}1}$${\mathit{d}}_{5/2}$) and (${\mathit{p}}_{3/2}^{\mathrm{\ensuremath{-}}1}$${\mathit{d}}_{5/2}$) configurations have been deduced. Comparison with previous work shows general agreement except for the T=0,${\mathit{J}}^{\mathrm{\ensuremath{\pi}}}$=${3}^{\mathrm{\ensuremath{-}}}$ term.

The Gamow-Teller (GT) transition strengths in fp-shell nuclei are important parameters in presupernova models. A high-energy-resolution (He-3,t) experiment was performed on the T-z=1 nucleus Ti-46 at 0(degrees) and at an intermediate incident energy of 140 MeV/nucleon for the study of precise GT transition strengths to the final T-z=0 nucleus V-46. With an energy resolution of 33 keV, individual GT transitions were observed and GT strengths were derived for them up to the excitation energy of 4.5 MeV. The GT strengths were compared with shell-model calculations using various effective interactions. In this low-lying region, most GT states have isospin T=0. A few GT states with isospin T=1 were identified from the existence of the corresponding (analog) M1 states in Ti-46. By comparing the GT strength with the corresponding (analogous) M1 transition strength studied in Ti-46(e,e(')) or (gamma,gamma(')) measurements, a large constructive interference of orbital and spin terms was suggested for one of these M1 transitions.

The Tri$\mu$P facility at KVI is dedicated to provide short lived radioactive isotopes at low kinetic energies to users. It comprised different cooling schemes for a variety of energy ranges, from GeV down to the neV scale. The isotopes are produced using beam of the AGOR cyclotron at KVI. They are separated from the primary beam by a magnetic separator. A crucial part of such a facility is the ability to stop and extract isotopes into a low energy beamline which guides them to the experiment. In particular we are investigating stopping in matter and buffer gases. After the extraction the isotopes can be stored in neutral atoms or ion traps for experiments. Our research includes precision studies of nuclear $\beta$-decay through $\beta$-$\nu$ momentum correlations as well as searches for permanent electric dipole moments in heavy atomic systems like radium. Such experiments offer a large potential for discovering new physics., Comment: COOL05 Workshop, Galena, Il, USA, 18-23. Sept. 2005, 5 pages, 3 figures

The Ni-58 (t, He-3)Co-58 reaction at 112 MeV/nucleon was measured to identify strength associated with Gamow-Teller transitions in the T-z = +1 direction. The experiment is a test case for future similar studies. The main aim of such studies is to test theoretical models used to predict Gamow-Teller strength distributions that serve as input for supernovae evolution calculations. The results indicate that the (t, He-3) reaction is indeed a powerful tool to perform such tests.

A high energy-resolution $^{11}\mathrm{B}(^{3}\mathrm{He},t)^{11}\mathrm{C}$ experiment was performed at $0\ifmmode^\circ\else\textdegree\fi{}$ and an intermediate incident energy of $140\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}∕\mathrm{nucleon}$ for the study of precise Gamow-Teller (GT) transition strengths. Two doublet states at $\ensuremath{\approx}4.5$ and $\ensuremath{\approx}8.4\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}$ were clearly resolved with a resolution of $45\phantom{\rule{0.3em}{0ex}}\mathrm{keV}$. The strengths are compared with a calculation using an ab initio no-core shell model, which became available for the $A=11$ system recently. It was found that a calculation including a three-nucleon interaction better reproduces the observed GT transition strengths.

The extension of singles (p↘,p↘′) studies to include coincident (p↘,p′γ) measurements can provide new information about the effective nucleon–nucleus interaction. We have therefore made simultaneous measurements of (p↘,p↘′) and (p↘,p′γ) observables for the 15.11 MeV, 1+, T=1 state in 12C at an incident beam energy of 200 MeV. Contained in these coincident observables are determinations of the sideways and longitudinal analyzing powers, D0S and D0L, which must vanish in singles measurements due to parity conservation. With this large data set on a transition with a relatively simple spin sequence, we have, in principle, enough information for a complete determination of the scattering amplitude.

A new three‐magnet Chicane combined with an existing K300 Spectrometer are planned for installation in the S‐straight section of the IUCF Cooler ring. Some classes of physics experiments accessible to this system and a description of the experimental layout are given.

Angular distributions of the differential cross section and vector analyzing power have been measured for the reactions 13 C ( d , t ) 12 C , 13 C ( d , p ) 14 C and inelastic scattering, 13 C ( d , d ′) 13 C . The states analyzed are the 0+ ground state, 4.44 MeV, 2+ state and the 7.66 MeV, 0+ state in 12C; the 0+ ground state, 6.09 MeV, 1− state and the 7.34 MeV, 2− state in 14C; and the 1 2 − ground state, 3.09 MeV, 1 2 + state, 3.68 MeV, 3 2 − state, and the 3.85 MeV, 5 2 + state in 13C. Optical model parameters for the deuteron channel are obtained by fitting the elastic scattering data. DWBA and coupled-channels calculations are made for the states reached through the (d, t) reaction. DWBA calculations for the (d, p) reaction are also shown. Coupled-channels and microscopic calculations are compared with the inelastic scattering data. The calculated vector analyzing power for scattering to the positive parity states in 13C is found to be very sensitive to the reaction mechanism chosen.

Angular distributions of vector analyzing power and cross section for the 37 Cl( d , t) 36 Cl reaction leading to the first five positive parity levels in 36 Cl and the deuteron elastic scattering 3 Cl( d , d 0 ) have been measured at an incident deuteron energy of 12.0 MeV. Deuteron optical model parameters were obtained by fitting the cross section and analyzing power of the measured deuteron elastic scattering. The DWBA analysis of the ( d , t) results shows that the ground state and the first excited state are populated mainly by a l n = 2, j n = 3 2 neutron transfer while for the higher excited states several values of j n contribute significantly.

Differential cross sections for the 209Bi(d, 3He)208Pb transitions to the proton particle-proton hole states in 208Pb were obtained with the 45 MeV analyzed deuteron beam from the JULIC cyclotron and the high resolution spectrograph BIG KARL. 72 states up to 6.6 MeV were studied with an overall resolution of 12 to 15keV. Spectroscopic factors were extracted relative to the simultaneously measured calibration reaction 208Pb(d, 3He)207Tl. For 26 states new parity assignments were possible on the basis of the measured angular distributions. The deduced inclusion into one of the four multiplets put limits on the possible spins of the states in question. With the help of sum rule arguments the spins of 12 states were assigned. The comparison with shell model calculations give only rough agreement as they predict the energies of the respective states about 300 keV too high. The magnetic dipole state at 5.846 MeV was observed with a Spectroscopic factor C2S = 0.17. From this, together with the transition probability B(M1↑) = (1.6 ± 0.5) μN2 from a ( γ , γ′) experiment we derived size and relative sign of the dominant neutron and proton spin-flip amplitudes. The result gives clear evidence for the isoscalar character of this state in accordance wtih TDA and RPA predictions. The matrix elements of the two-body residual interaction were derived unambiguously for the h 9 2 ∗ s 1 2 and h 9 2 ∗ d 3 2 multiplets. For the h 9 2 ∗ h 11 2 and h 9 2 ∗ d 5 2 multiplets uncertainties are larger because of assumptions of some of the spins for the states of high excitation energy. The four monopole terms are found close to the average of −308 keV. They are dominated by the Coulomb contributions of ≈ − 216 keV. The deduced J-dependence of the matrix elements differs from those found in other systematic investigations indicating more complicated underlying nuclear forces must contribute.

The first three states in 21Ne (ground state 3 2 + , 0.35 MeV 5 2 + and 1.75 MeV 7 2 + ) were studied with the 20Ne( d , p)21Ne reaction. Differential cross section and vector analyzing power angular distributions at 7 energies between 10 and 12 MeV were measured. In addition, excitation functions for the differential cross section were obtained for these three states, between 9 and 13 MeV in steps of 50 keV, at four backward scattering angles of 90, 108.3, 131.7 and 150 degrees. A statistical analysis of the observed fluctuations was performed to separate the compound-nuclear contribution to the cross section from the direct contribution. A quantitative estimate of the compound contribution could be made since the absolute normalization of the Hauser-Feshbach calculation was determined from the fluctuation analysis. The energy-averaged angular distributions were compared to the sum of compound and direct calculations. For the 5 2 + state a one-step direct-reaction calculation was found to be reasonably adequate. Calculations were compared with the data for all three transitions using the coupled-channels approach with spectroscopic amplitudes obtained from a shell-model calculation. In general, the fits to the data were not very good. Elastic and inelastic deuteron scattering to the ground state 0+ and to the excited 2+ state were also measured. These data were compared to optical-model and coupled-channels calculations.

Angular distributions of the 12 C(d, 6 Li) 8 Be reaction at E lab = 78.0 MeV and the 11 B( 3 He, 6 Li) 8 Be reaction at E lab = 71.8 MeV were measured. Transitions leading to 8 Be in the ground state and the 3.04, 16.63, 16.92, 17.64 and 18.15 MeV excited states were observed. A DWBA analysis was performed regarding the (d, 6 Li) and ( 3 He, 6 Li) reactions as direct α particle or triton transfers, respectively.

Angular distributions of the 11 B( 3 He, 7 Li) 7 Be reaction were measured in the entire angular region at 71.8 MeV beam energy yielding information on the 4 H-like cluster transfer in the forward direction and α-cluster transfer in the backward region. A DWBA analysis including processes up to the second order indicates a rather small yield of 4 H transfer and a dominant two-step transfer mechanism in the ( 3 He, 7 Li) reaction.

Angular distributions of the vector analyzing power and the absolute cross section were measured for 24Mg( d , p)25Mg at nine energies between 10 and 12 MeV and energy averaged angular distributions were obtained. Excitation functions of the cross section from about 8 to 13 MeV were measured for the first five excited states in 25Mg at three backward scattering angles θlab = 105°, 138° and 160°. A statistical analysis of the observed fluctuations was employed to separate the direct and the compound nuclear contribution. These results allowed the absolute normalization of Hauser-Feshbach calculations and a quantitative estimate of compound nuclear effects on cross section and vector analyzing power. The energy averaged angular distributions of the first four stripping states in the residual nucleus are compared with DWBA calculations. The transition to 7 2 + state at Ex = 1.61 MeV is found to proceed almost entirely by a compound nuclear mechanism. Spins J, parities π and spectroscopic factors C2Sij of six higher excited states were determined.

Experimental evidence is presented that the144Nd(p, α)141Pr reaction excites residual nucleus levels with a dominant single proton configuration, suggesting a contribution from knock-on mechanism.

In a high resolution (p,p′) experiment at E=25.5MeV, the complete particle-core coupled multiplet (3 − · f 7 2 ) J in the N=83 143Nd nucleus has been identified and the spins of its members assigned. The experimental results are discussed in connection with the observed large energy splitting of about 650 keV. The comparison with the corresponding multiplet observed in 146Gd is a new strong indication for the shell closure at Z=64.

Inelastic excitation of giant resonances has been studied in 172 MeV $\ensuremath{\alpha}$ scattering from $^{208}\mathrm{Pb}$ at scattering angles of 1.5\ifmmode^\circ\else\textdegree\fi{}-8\ifmmode^\circ\else\textdegree\fi{}. Fine structures in the region of the giant monopole and quadrupole resonances indicate multipolarities also different from $L=0 \mathrm{and} 2$. The isoscalar $L=0 \mathrm{and} 2$ strengths in the giant resonance region yield (90\ifmmode\pm\else\textpm\fi{}20)% and (70\ifmmode\pm\else\textpm\fi{}20)% of the corresponding energy weighted sum rule limit. This is consistent with other hadron scattering results, with higher energy electron scattering, and with microscopic random phase approximation results. However, the strength for $L=2$ excitations is significantly larger than extracted from lower energy electron scattering. Fine structures observed are compared with high resolution (p,p\ensuremath{'}) and (e,e\ensuremath{'}) results. At scattering angles 5\ifmmode^\circ\else\textdegree\fi{}-8\ifmmode^\circ\else\textdegree\fi{} new structures have been observed at ${E}_{x}=12.5 \mathrm{and} 16.0$ MeV consistent with multipolarities $L=4 \mathrm{and} 6$. Together with the contribution of higher multipolarity extracted at lower excitation energies from the angular distributions of giant monopole and quadrupole excitations, this indicates rather broad distributions of $2\ensuremath{\hbar}\ensuremath{\omega}$ $L=4 \mathrm{and} 6$ excitations with centroid energies of 12.2 and 13.7 MeV and widths of 4.5 and 7.8 MeV, respectively. The extracted sum rule strengths for $L=4 \mathrm{and} 6$ are in the order of 30% in each case. In the region of the giant monopole resonance evidence for additional $L=2$ excitation was found (\ensuremath{\le}14% energy weighted sum rule strength). The fact that strong contributions of $Lg0$ are obtained solves the problem of a former too large monopole cross section in $\ensuremath{\alpha}$ scattering which was inconsistent with microscopic descriptions. A recently suggested "antiscaling" mode for the giant monopole resonance, in which the nuclear surface vibrates opposite in phase to the "scaling" mode, can be ruled out by our experimental data. The existence of two odd parity giant resonances at ${E}_{x}=18.7$ MeV ($L=3$) MeV ($L=1$) with widths of 5.0 and 5.9 MeV, respectively, are confirmed by our small angle scattering experiments. Our description of the dipole compressional mode is in excellent agreement with 200 MeV proton scattering data.NUCLEAR REACTIONS $^{208}\mathrm{Pb}(\ensuremath{\alpha}, {\ensuremath{\alpha}}^{\ensuremath{'}})$; ${E}_{\ensuremath{\alpha}}=172$ MeV. Small angle scattering, $\ensuremath{\theta}=1.5\ifmmode^\circ\else\textdegree\fi{}\ensuremath{-}8\ifmmode^\circ\else\textdegree\fi{}$; measured $\ensuremath{\sigma}(\ensuremath{\theta})$. Deduced excitation strength distributions for giant resonances of multipolarities $L=0\ensuremath{-}6$.

Differential cross sections and analyzing powers for/sup 15/N(/ital d/rvec //,/ital t/)/sup 14/N were measured up to 25MeV excitation energy with 88 and 89 MeV polarized deuteron beams and magneticspectrographs. States of /sup 14/N up to 18.53 MeV have been studiedin two experiments with overall resolutions of 25--70 keV, and /ital j/transfers were determined from their characteristic analyzing powers. Mixturesof different /ital j/ transfers could be determined for those 1/sup +/states where mixing was significant. Exact finite-range distorted-wave Bornapproximations calculations were used to deduce /ital l/ transfers andspectroscopic strengths. The observed summed spectroscopic strength is 88% ofthe shell-model sum rule. Firm lower limits and tentative upper limits for six(/ital p//sub 1/2/p/sub 1/2/)/sub J,/ital T// and(/ital p//sub 3/2/p/sub 1/2/)/sub J,/ital T// residual two-nucleonmatrix elements are deduced. Comparison with the widely used Cohen-Kurathmatrix elements shows good agreement for four terms, but significantquantitative disagreement for the(/ital p//sub 1/2/p/sub 1/2/)/sub 0/sup +/,1/ and(/ital p//sub 1/2/p/sub 3/2/)/sub 1/sup +/,1/ terms.We also see significantly more than the predicted/ital p//sub 1/2/p/sub 3/2/ mixing for the 3.948 MeV1/sup +/,0 state. No appreciable pickup of /ital s/-/ital d/shell admixtures was seen up to 25 MeV excitation.

Target thickness dependences of3He1+ yields from Al, Ni, Ag and Au targets were measured at 68, 99 and 130 MeV incident3He2+ energies, leading to electron stripping and capture cross sections. The results are compared with current theories.