Recent data on isoscalar giant monopole resonance (ISGMR) in the calcium isotopes 40,44,48Ca have suggested that Kτ, the asymmetry term in the nuclear incompressibility, has a positive value. A value ...of Kτ>0 is entirely incompatible with present theoretical frameworks and, if correct, would have far-reaching implications on our understanding of myriad nuclear and astrophysical phenomena. This paper presents results of an independent ISGMR measurement with the 40,42,44,48Ca(α,α′) reaction at Eα=386 MeV. These results conclusively discount the possibility of a positive value for Kτ, and are consistent with the previously-obtained values for this quantity.
•An overview of the FRS Ion Catcher experiment at GSI is given.•The FRS Ion Catcher consists of the FRS, a cryogenic stopping cell, an RF quadrupole-based beam transport and diagnostics unit and a ...multiple-reflection time-of-flight mass spectrometer.•Off-line tests of the stopping cell with 219Rn ions.•First on-line operation of a stopping cell for exotic nuclei at cryogenic temperatures.•First mass measurements of heavy projectile fragments using a multiple-reflection time-of-flight mass spectrometer.
At the FRS Ion Catcher at GSI, projectile and fission fragments are produced at relativistic energies, separated in-flight, range-focused, slowed down and thermalized in a cryogenic stopping cell. A multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) is used to perform direct mass measurements and to provide an isobarically clean beam for further experiments, such as mass-selected decay spectroscopy. A versatile RF quadrupole transport and diagnostics unit guides the ions from the stopping cell to the MR-TOF-MS, provides differential pumping, ion identification and includes reference ion sources. The FRS Ion Catcher serves as a test facility for the Low-Energy Branch of the Super-FRS at the Facility for Antiproton and Ion Research (FAIR), where the cryogenic stopping cell and the MR-TOF-MS will be key devices for the research with stopped projectile and fission fragments that will be performed with the experiments MATS and LaSpec. Off-line tests of the stopping cell yield a combined ion survival and extraction efficiency for 219Rn ions of about 30% and an extraction time of about 25ms. The stopping cell and the MR-TOF-MS were commissioned on-line as part of the FRS Ion Catcher. For the first time, a stopping cell for exotic nuclei was operated on-line at cryogenic temperatures. Using a gas density almost two times higher than ever reached before for a stopping cell with RF ion repelling structures, various 238U projectile fragments were thermalized and extracted with very high efficiency. Direct mass measurements of projectile fragments were performed with the MR-TOF-MS, among them the nuclide 213Rn with a half-life of 19.5ms only.
Analysis of the data acquired with the BINA detector system in
1
H(
d
,
pp
)
n
reaction at the beam energy of 80 MeV/nucleon makes a systematic analysis of the star configurations possible. This ...paper shows the preliminary cross section of the Forward-Plane Star (FPS) configuration with the neighbouring configurations.
.
Precision measurements of vector and tensor analyzing powers of the
2
H(
d
,
dp
)
n
break-up process for configurations in the vicinity of the quasi-free scattering regime with the neutron as ...spectator are presented. These measurements are performed with a polarized deuteron-beam with an energy of 65MeV/nucleon impinging on a liquid-deuterium target. The experiment was conducted at the AGOR facility at KVI using the BINA 4
π
-detection system. Events for which the final-state deuteron and proton are coplanar have been analyzed and the data have been sorted for various momenta of the missing neutron. In the limit of vanishing neutron momentum and at large deuteron-proton momentum transfer, the data agree well with the measured and theoretically predicted spin observables of the elastic deuteron-proton scattering process. The agreement deteriorates rapidly with increasing neutron momentum and/or decreasing momentum transfer from the deuteron beam to the outgoing proton. This study reveals the presence of a significant contribution of final-state interactions even at very small neutron momenta.
We have measured for the first time simultaneously both the mean charge states and stopping powers of (35-280) MeV/u 208Pb ions in gases and solids with an accuracy of 1%. The existence at lower ...energies and disappearance at higher of density effects in the charge-state distribution and the corresponding stopping power are directly confirmed and comparisons with widely used theories and simulations for heavy ions demonstrate strong deviations of up to 27%. However, an unprecedented prediction power of better than 3% has been achieved for the energy loss when the measured mean charge-states are implemented in the Lindhard-Sørensen theory. Our present benchmark data contribute to an improved understanding of the basic atomic collision processes and to numerous applications in nuclear physics. Extending the GANIL data 1 to higher accuracy and energies, we can now answer at which velocities the Bohr-Lindhard density effect in stopping will vanish.
Vector-analyzing powers,
A
x
and
A
y
, of the proton–deuteron break-up reaction have been measured by using a polarized-proton beam at 135 MeV impinging on a liquid-deuterium target. For the ...experiment, the big instrument for nuclear-polarization analysis (BINA) was used at KVI, Groningen, the Netherlands. The data are compared to the predictions of Faddeev calculations using state-of-the-art two- and three-nucleon potentials. Our data are reasonably well described by calculations for the kinematical configurations at which the three-nucleon force (3NF) effect is predicted to be small. However, striking discrepancies are observed at specific configurations, in particular in the cases of symmetric configurations, where the relative azimuthal angle between the two protons is small which corresponds to the
d
(
p
→
,
2
He
)
n
channel. The vector-analyzing powers of these configurations are compared to the proton–deuteron elastic scattering to study the spin–isospin sensitivity of the 3NF models. The results are compared to the earlier results of the proton–deuteron break-up reaction at 190 MeV proton-beam energy
1
. Disagreement is observed for both proton-beam energies between data and calculations which points to a deficiency in the treatment of spin–isospin part of the 3NF.
A selection of measured cross sections and vector analyzing powers,
A
x
and
A
y
, are presented for the
p
→
d
break-up reaction. The data are taken with a polarized proton beam with a kinetic energy ...of 135 MeV using the Big Instrument for Nuclear-polarization Analysis (BINA) at KVI, the Netherlands. With this setup,
A
x
is extracted for the first time for a large range of energies as well as polar and azimuthal angles of the two outgoing protons. For most of the configurations, the results at small and large relative azimuthal angles differ in behavior when comparing experimental data with the theoretical calculations. We also performed a more global comparison of our data with theoretical calculations. The cross-section results show huge values of
χ
2
/d.o.f.. The absolute values of
χ
2
/d.o.f. for the components of vector analyzing powers,
A
x
and
A
y
, are smaller than the ones for the cross section, partly due to larger uncertainties for these observables. However, also for these observables no satisfactory agreement is found for all angular combinations. This implies that the present models of a three-nucleon force are not able to provide a satisfactory description of experimental data.
A cryogenic stopping cell for stopping energetic radioactive ions and extracting them as a low energy beam was developed. This first ever cryogenically operated stopping cell serves as prototype ...device for the Low-Energy Branch of the Super-FRS at FAIR. The cell has a stopping volume that is 1m long and 25cm in diameter. Ions are guided by a DC field along the length of the stopping cell and by a combined RF and DC fields provided by an RF carpet at the exit-hole side. The ultra-high purity of the stopping gas required for optimum ion survival is reached by cryogenic operation. The design considerations and construction of the cryogenic stopping cell, as well as some performance characteristics, are described in detail. Special attention is given to the cryogenic aspects in the design and construction of the stopping cell and the cryocooler-based cooling system. The cooling system allows the operation of the stopping cell at any desired temperature between about 70K and room temperature. The cooling system performance in realistic on-line conditions at the FRS Ion Catcher Facility at GSI is discussed. A temperature of 110K at which efficient ion survival was observed is obtained after 10h of cooling. A minimum temperature of the stopping gas of 72K was reached. The expertise gained from the design, construction and performance of the prototype cryogenic stopping cell has allowed the development of a final version for the Low-Energy Branch of the Super-FRS to proceed.
Detailed measurements of five-fold differential cross sections and a rich set of vector and tensor analyzing powers of the
2
H
(
d
,
d
p
)
n
break-up process using polarized deuteron-beam energy of ...65 MeV/nucleon with a liquid-deuterium target are presented. The experiment was conducted at the AGOR facility at KVI using the BINA 4
π
-detection system. We discuss the analysis procedure including a thorough study of the systematic uncertainties. The results can be used to examine upcoming state-of-the-art calculations in the four-nucleon scattering domain, and will, thereby, provide further insights into the dynamics of three- and four-nucleon forces in few-nucleon systems. The results of coplanar configurations are compared with the results of recent theoretical calculations based on the Single-Scattering Approximation (SSA). Through these comparisons, the validity of SSA approximation is investigated in the Quasi-Free (QF) region.
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