Liquid-gas phase transition in nuclear multifragmentation

The equation of state of nuclear matter suggests that at suitable beam energies the disassembling hot system formed in heavy ion collisions will pass through a liquid-gas coexistence region. Searching for the signatures of the phase transition has been a very important focal point of experimental endeavours in heavy ion collisions, in the last fifteen years. Simultaneously theoretical models have been developed to provide information about the equation of state and reaction mechanisms consistent with the experimental observables. This article is a review of this endeavour.Comment: 63 pages, 27 figures, submitted to Adv. Nucl. Phys. Some typos corrected, minor text change

Proton and neutron knockout from 36Ca

The cross sections for single-nucleon knockout from Ca-36 on a Be-9 target at 70 MeV/nucleon were measured to be sigma(exp)(-p) = 51.1 +/- 2.6 mb for proton knockout and sigma(exp)(-n) = 5.03 +/- 0.46 mb for neutron knockout. The spectroscopic factors and orbital angular momenta of the neutrons and protons removed from Ca-36, leading to bound A = 35 residues, were deduced by comparison of the experimental cross sections and longitudinal- momentum distributions to those calculated in an eikonal reaction theory, and found to be S(p, 1d(3/2)) = 0.79 +/- 0.04 and S(n, 2s(1/2)) = 0.23 +/- 0.02 (relative to independent-particle-model values and only including experimental contributions to the uncertainties). As found in previous knockout studies, the spectroscopic factor deduced for the deeply bound neutron was significantly reduced relative to shell-model calculations, a result at variance with dispersive optical model (DOM) extrapolations, which suggest a spectroscopic factor closer to 60% of the independent-particle-model value

Proton and neutron knockout from 36Ca

The cross sections for single-nucleon knockout from Ca-36 on a Be-9 target at 70 MeV/nucleon were measured to be sigma(exp)(-p) = 51.1 +/- 2.6 mb for proton knockout and sigma(exp)(-n) = 5.03 +/- 0.46 mb for neutron knockout. The spectroscopic factors and orbital angular momenta of the neutrons and protons removed from Ca-36, leading to bound A = 35 residues, were deduced by comparison of the experimental cross sections and longitudinal- momentum distributions to those calculated in an eikonal reaction theory, and found to be S(p, 1d(3/2)) = 0.79 +/- 0.04 and S(n, 2s(1/2)) = 0.23 +/- 0.02 (relative to independent-particle-model values and only including experimental contributions to the uncertainties). As found in previous knockout studies, the spectroscopic factor deduced for the deeply bound neutron was significantly reduced relative to shell-model calculations, a result at variance with dispersive optical model (DOM) extrapolations, which suggest a spectroscopic factor closer to 60% of the independent-particle-model value

Prompt Proton Decay Scheme of 59Cu

Five prompt proton decay lines have been identified between deformed states in Cu-59 and three spherical states in Ni-58 by means of high-resolution in-beam particle-gammagamma coincidence spectroscopy. The GAMMASPHERE array coupled to dedicated ancillary detectors including four DeltaE-E silicon strip detectors was used to study high-spin states in Cu-59. The multiple discrete proton lines are found to probe the wave functions of states in the decay-out regime of well- and superdeformed states

High-resolution In-beam Particle Spectroscopy - New Results on Prompt Proton Emission from 58Cu

Prompt proton decay lines in Cu-58 have been studied by means of high-resolution in-beam particle-gamma coincidence spectroscopy using the GAMMASPHERE Ge-detector array in conjunction with a dedicated set of ancillary detectors including four DeltaE-E silicon-strip telescopes. High-spin states in Cu-58 have been populated via the heavy-ion fusion-evaporation reaction Si-28(Ar-36, 1alpha1p1n) at 148 MeV beam energy. The full-width at half maximum for the proton peak could be reduced significantly compared to earlier experiments. The results indicate that only one prompt proton decay branch exists in the decay-out of the well-deformed band of Cu-58

Neutron spectroscopic factors of Ar-34 and Ar-46 from (p,d) transfer reactions

Single-neutron-transfer measurements using (p,d) reactions have been performed at 33 MeV per nucleon with proton-rich Ar-34 and neutron-rich Ar-46 beams in inverse kinematics. The extracted spectroscopic factors are compared to the large-basis shell-model calculations. Relatively weak quenching of the spectroscopic factors is observed between Ar-34 and Ar-46. The experimental results suggest that neutron correlations have a weak dependence on the asymmetry of the nucleus over this isotopic region. The present results are consistent with the systematics established from extensive studies of spectroscopic factors and dispersive optical-model analyses of Ca40-49 isotopes. They are, however, inconsistent with the trends obtained in knockout-reaction measurements

Neutron spectroscopic factors of Ni-55 hole-states from (p, d) transfer reactions

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 Cu), one nucleon away from 56 Ni, the N = Z = 28 double magic nucleus. Using the H1(Ni56,d)Ni55 transfer reaction in inverse kinematics, neutron spectroscopic factors, spins and parities have been extracted for the f7/2 , p3/2 and the s1/2 hole-states of 55 Ni. These new data provide 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 s1/2 hole-state below Fermi energy. © 2014 The Authors.status: publishe

What are the prospects for continued low fertility in Japan?

The low-fertility trap hypothesis (Lutz, Skirbekk, Testa, Vienna Yearb Popul Res 4:167-192) describes plausible self-reinforcing mechanisms that, if unchecked, would result in a continued decrease of the number of births in countries affected. It postulates that (a) low birth rates lead to fewer women of reproductive age; (b) fertility preferences shaped early in life lead to lower fertility preferences and lower realized fertility in adulthood for generations who have grown up with few siblings; and (c) growing material aspirations lead many couples to postpone childbearing, especially when the relative income of the young decreases. This chapter investigates whether Japan is in a low-fertility trap and finds clear evidence of the first mechanism (rapidly shrinking cohorts of reproductive age), some evidence of the second (value changes resulting in further fertility decline) and some support for the third mechanism (declining relative income among young adults, implying postponed and depressed fertility). Provided that aspirations of young adults grow while the expected income for younger cohorts decreases, partly as a consequence of population aging induced by low fertility, Japan's fertility could further decline as all three factors would then work toward creating a downward spiral in births. If such mechanisms are indeed at work, this should prompt governments to take action to avoid the trap while that is still possible