Performance of the large-acceptance gas-filled spectrometer VAMOS

Saturday 3 April 2010, by Antoine Lemasson // Peer reviewed publications

A new gas-filled operation mode of the large-acceptance spectrometer VAMOS at GANIL is reported. A beam rejection factor greater than 1010 is obtained for the 40Ca+150Sm system at 196 MeV. The unprecedented transmission efficiency for the evaporation residues produced in this reaction is estimated to be around 80% for alpha xn channels and above 95% for xn-yp channels. A detailed study of the performance of the gas-filled VAMOS and future developments are discussed. This new operation mode (...) Read next

Physics Viewpoint

A 21st century Rutherford experiment

Monday 30 November 2009, by Antoine Lemasson // Peer reviewed publications

Our recent Phys. Rev. Lett. "Modern Rutherford experiment : Tunnelling of the most neutron-rich nucleus" was the subject of a Physics "Viewpoint" : A 21st century Rutherford experiment from Dieter Ackermann and Haik Simon. Physics highlights exceptional papers from the Physical Review journals. Read the Viewpoint on physics.aps.org Press Release : L’expérience fondatrice de Rutherford revisitée Read the CEA (Commissariat à l’Energie Atomique) Press Release Read the CNRS (Centre (...) Read next

Physical Review Letter

Modern Rutherford experiment : Tunnelling of the most neutron-rich nucleus

Monday 30 November 2009, by Antoine Lemasson // Peer reviewed publications

A modern variation of the Rutherford experiment to probe the tunneling of exotic nuclear matter from the measurement of the residues formed in the bombardment of 197Au by extremely neutron-rich 8He nuclei is presented. Using a novel off-beam technique the most precise and accurate measurements of fusion and neutron transfer involving re-accelerated unstable beams are reported. The results show unusual behavior of the tunneling of 8He compared to that for lighter helium isotopes, (...) Read next

Physical Review C : Rapid Com.

Prompt γ-ray spectroscopy of isotopically identified fission fragments

Friday 27 November 2009, by Antoine Lemasson // Peer reviewed publications

Measurements of prompt Doppler-corrected deexcitation γ-rays from uniquely identified fragments formed in fusion-fission reactions of the type 12C(238U,134Xe)Ru are reported. The fragments were identified in both A and Z using the magnetic spectrometer VAMOS. States built on the characteristic neutron configurations forming high spin isomers (7^− and 10+) in 134Xe are presented and compared with the predictions of shell-model calculations using a new effective interaction in the region of Z > (...) Read next

Physical Review Letter

Exploring fusion at extreme sub-barrier energies with weakly bound nuclei

Tuesday 3 November 2009, by Antoine Lemasson // Peer reviewed publications

Results of measurement of residues formed in fusion of 6Li with 198Pt in the energy range of 0.68< E/Vb <1.3 using a new sensitive off-beam technique are reported. The fusion excitation function and the derived average angular momenta do not indicate a change of slope at deep sub- barrier energies, contrary to recent observations. The present results for a system with weakly bound projectile confront the current understanding of the fusion hindrance at these low (...) Read next

1n- and 2n-transfer with the Borromean nucleus 6He near the Coulomb barrier

Saturday 4 July 2009, by Antoine Lemasson // Peer reviewed publications

Angular distributions for 1n- and 2n-transfer are reported for the 6He + 65Cu system at Elab = 22.6 MeV. For the first time, triple coincidences between particles, neutrons and characteristic rays from the target-like residues were used to separate the contributions arising from 1n- and 2n-transfer. The differential cross sections for these channels, elastic scattering, and fusion were analyzed using a Coupled Reaction Channels approach. The large measured ratio of the 2n/1n cross section (...) Read next

Absolute cross-sections from X-γ coincidence measurements

Saturday 4 July 2009, by Antoine Lemasson // Peer reviewed publications

An activation technique using coincidences between characteristic X-rays and γ-rays to obtain absolute cross-sections is described. This method is particularly useful in the case of nuclei that decay by electron capture. In addition to the reduction of possible contamination, an improved detection sensitivity is achieved as compared to inclusive measurements, thereby allowing the extraction of absolute fusion cross-sections in the nano-barn range. Results of this technique for 6Li+198Pt (...) Read next