S. Gales

Evidence for the radioactive decay of 226Ra by 14C emission

Using a magnetic spectrometer and an intense 226Ra source, first evidence for the radioactive decay of 226Ra by 14C emission was obtained leading to a measured branching ratio relative to α-particles of (3.2±1.6)×10−11. In addition, the decay of 222Ra by 14C emission, previously reported, was clearly observed and an upper limit was set for the emission of 34Si from 241Am.

Spin of deep-hole states in 111Sn via the 112Sn(d, t) reaction

Abstract Analyzing powers measured in the study of 112 Sn ( d , t ) at 40 MeV bombarding energy show strong J-dependence and have been used to clearly assign the spin of a number of low-lying states in the residual nucleus. At high excitation energy (3.5–6 MeV). the inner-hole strength is shared between clearly isolated peaks on one hand and a fragmented structure on the other. This work reports on the determination of the spin of the inner-hole states and consequently on a more precise measurement of the overlapping regions between 1 g 9 2 , 2 p 1 2 , 2 p 3 2 Subshell components. The analyzing power data shows that the group of peaks located between 3.4 and 4.5 MeV consist of spins J = 9 2 + 1 2 , in agreement with the excitation of the 1 g 1 2 and 2 p 1 2 inner- hole strengths in 111Sn. In addition a substantial amount of the 2 p 3 2 component is observed between 4.5 and 6.0 MeV. The results of the data analysis allow us to clearly eastablish the spreading of the 1 g 9 2 innerhole strength and to a lesser extent the strong fragmentation of the 2 p 1 2 and 2 p 3 2 inner-hole subshells.

High lying two-neutron hole states in 206Pb and 114Sn observed via the (α, 6He) reaction at 218 MeV

Abstract Strong enhancements of two-neutron hole states are observed in a (α, 6 He) reaction study at 218 MeV on 208 Pb and 114 Sn target nuclei. Selective population of high-spin states, characteristic patterns of the angular distributions and successful direct one-step analysis of the data are the main attractive features of the (α, 6 He) process at high incident energy. As illustrative examples, spin and configurations of levels or structures in 206 Pb and 114 Sn are reported.

Angular correlation studies of isobaric analog states in 49Sc via the 48Ca(τ,dp)48Ca reaction

Abstract A new method for studying the proton decay of isobaric analog states is proposed. The proton decay of highly excited analog states, populated by the (τ,d) reaction, is investigated using method II of Litherland and Ferguson. Spins and proton partial widths for transitions to the ground and excited states of the target are extracted by means of d - p angular correlation measurements. The method is illustrated by a study of analog states in 49 Sc.

Recherche de résonances isobariques analogues dans 32S AU moyen des réactions 31P(p, γ)32S 31P(p, p)31P et 31P(p, α0)28Si

Abstract Fourteen resonance levels have been observed in a study of the 31 P(p, γ) 32 S, 31 P(p, p) 31 P and 31 P(p, α 0 ) 28 Si reactions in the proton energy range E p = 1240–1600 keV. Resonance strengths have been determined for thirteen resonances of the 31 P(p, γ) 32 S reaction. The γ-ray decay schemes often resonances have been studied by means of a Ge(Li) detector. Spin values of resonance levels and of some bound levels have been obtained or confirmed by γ-ray angular distribution measurements done at seven resonances. For the thirteen resonances of the 31 P(p, p) 31 P reaction the proton orbital momenta have been determined. By combining the information from the three reactions, spins, parities, total and partial widths have been obtained for twelve resonance levels. Strong Ml transitions have been observed at the E p = 1247, 1402, 1437, 1555 and 1581 keV resonances. Two T -mixed doublets are identified at E p = 1247 and 1472 keV, J π = 2 − , and at E p = 1402 and 1469 keV, J π = 3 − . The resonance levels at E p = 1437 and 1581 keV may be components of a third almost completely mixed doublet. The E p = 1555 keV resonance level has been assigned T = 1. The E p = 1411 keV, J π = 1 + , resonance level has been identified with a level previously observed in the β + decay of 32 Cl. Strong E2 transitions similar to those observed in some other doubly even s-d shell nuclei have been observed between odd-parity levels of 32 S.

Extreme light infrastructure nuclear physics (ELI-NP): present status and perspectives

Extreme Light Infrastructure (ELI) Pan-European facility initiative represents a major step forward in quest for extreme electromagnetic fields. Extreme Light Infrastructure – Nuclear Physics (ELI-NP) is one of the three pillars of the ELI facility, that aims to use extreme electromagnetic fields for nuclear physics and quantum electrodynamics research. At ELI-NP, high power laser systems together with a very brilliant gamma beam are the main research tools. Their targeted operational parameters are described. The related experimental areas are presented, together with the main directions of the research envisioned.

New frontiers in nuclear physics with high-power lasers and brilliant monochromatic gamma beams

The development of high power lasers and the combination of such novel devices with accelerator technology has enlarged the science reach of many research fields, in particular particle and nuclear physics, astrophysics as well as societal applications in material science, nuclear energy and applications for medicine. The European Strategic Forum for Research Infrastructures has selected a proposal based on these new premises called the Extreme Light Infrastructure (ELI). The ELI will be built as a network of three complementary pillars at the frontier of laser technologies. The ELI-NP pillar (NP for nuclear physics) is under construction near Bucharest (Romania) and will develop a scientific program using two 10 PW lasers and a Compton back-scattering high-brilliance and intense low-energy gamma beam, a combination of laser and accelerator technology at the frontier of knowledge. This unique combination of beams that are unique worldwide allows us to develop an experimental program in nuclear physics at the frontiers of present-day knowledge as well as society driven applications. In the present paper, the technical description of the facility as well as the new perspectives in nuclear structure, nuclear reactions and nuclear astrophysics will be presented.

Gamow-Teller strength for the analog transitions to the first T=1/2,J(pi)=3/2(-) states in (13)C and (13)N and the implications for type Ia supernovae

The Gamow-Teller strength for the transition from the ground state of (13)C to the T=1/2,J(pi)=3/2(-) excited state at 3.51 MeV in (13)N is extracted via the (13)C((3)He,t) reaction at 420 MeV. In contrast to results from earlier (p,n) studies on (13)C, a good agreement with shell-model calculations and the empirical unit cross-section systematics from other nuclei is found. The results are used to study the analog (13)N(e(-),nu(e))(13)C reaction, which plays a role in the pre-explosion convective phase of type Ia supernovae. Although the differences between the results from the ((3)He,t) and (p,n) data significantly affect the deduced electron-capture rate and the net heat deposition in the star resulting from this transition, the overall effect on the pre-explosive evolution is small.

Structure of from the (p, d) reaction in inverse kinematics

We have performed the Be reaction in inverse kinematics. The were detected in the SPEG spectrometer and the deuterons detected in a silicon array in coincidence. The yield to the first excited state of is greater than that to the ground state, and increases with angle. Strong population of the two-alpha plus two-neutron states near 6 MeV (in the two-centre shell-model description) is observed. The ultimate goal is to study the microscopic structure of from the extracted spectroscopic factors.

GANIL-SPIRAL2: a new era

GANIL presently offers unique opportunities in nuclear physics and in many other fields that arise from not only the provision of low-energy stable beams, fragmentation beams and re-accelerated radioactive species, but also from the availability of a wide range of state-of-the-art spectrometers and instrumentation. A few examples of recent highlights are presented. With the construction of SPIRAL2 over the next few years, GANIL is in a good position to retain its world-leading capability. As selected by the ESFRI committee, the next generation of ISOL facility in Europe is represented by the SPIRAL2 project to be built at GANIL (Caen, France). SPIRAL 2 is based on a high power, CW, superconducting LINAC, delivering 5 mA of deuteron beams at 40MeV (200KW) directed on a C converter+ Uranium target and producing therefore more 1013 fissions/s. The expected radioactive beams intensities in the mass range from A=60 to A=140, will surpass by two order of magnitude any existing facilities in the world. These unstable atoms will be available at energies between few KeV/n to 15 MeV/n. The same driver will accelerate high intensity (10?A to 1 mA), heavier ions (Ar up to Xe) at maximum energy of 14 MeV/n. Under the 7FP program of European Union called *Preparatory phase*, the SPIRAL2 project has been granted a budget of about 4M to build up an international consortium around this new venture. The scientific pillars of the future facility, the status of the construction of SPIRAL2 accelerator and associated physics instruments in collaboration with EU and International partners will be presented.