In gas laser ionization and spectroscopy experiments at the Superconducting Separator Spectrometer (S3): Conceptual studies and preliminary design

International audienceThe results of preparatory experiments and the preliminary designs of a new in-gas laser ionization and spectroscopy setup, to be coupled to the Super Separator Spectrometer S3 of SPIRAL2-GANIL, are reported. Special attention is given to the development and tests to carry out a full implementation of the in-gas jet laser spectroscopy technique. Application of this novel technique to radioactive species will allow highsensitivity and enhanced-resolution laser spectroscopy studies of ground- and excited-state properties of exotic nuclei

Structure of neutron-rich nuclei around the N = 50 shell-gap closure

International audienceThe structure of neutron-rich nuclei in the vicinity of 78Ni have been investigated via the beta-decay of 71,73,75Cu isotopes (ISOLDE, CERN). Experimental results have been compared with shell-model calculations performed with the ANTOINE code using a large (2p3/21 f5/22 p1/21 g9/2) valence space and a (56/28)Ni28 core

Consequences of anorectal cancer atlas implementation in the cooperative group setting: radiobiologic analysis of a prospective randomized in silico target delineation study

The aim of this study is to ascertain the subsequent radiobiological impact of using a consensus guideline target volume delineation atlas. Using a representative case and target volume delineation instructions derived from a proposed IMRT rectal cancer clinical trial, gross tumor volume (GTV) and clinical/planning target volumes (CTV/PTV) were contoured by 13 physician observers (Phase 1). The observers were then randomly assigned to follow (atlas) or not-follow (control) a consensus guideline/atlas for anorectal cancers, and instructed to re-contour the same case (Phase 2). The atlas group was found to have increased tumor control probability (TCP) after the atlas intervention for both the CTV (p <0.0001) and PTV1 (p=0.0011) with decreasing normal tissue complication probability (NTCP) for small intestine, while the control group did not. Additionally, the atlas group had reduced variance in TCP for all target volumes and reduced variance in NTCP for the bowel. In Phase 2, the atlas group had increased TCP relative to the control for CTV (p=0.03). Visual atlas and consensus treatment guideline usage in the development of rectal cancer IMRT treatment plans reduced the inter-observer radiobiological variation, with clinically relevant TCP alteration for CTV and PTV volume

PROSPECTIVE RANDOMIZED DOUBLE-BLIND PILOT STUDY OF SITE-SPECIFIC CONSENSUS ATLAS IMPLEMENTATION FOR RECTAL CANCER TARGET VOLUME DELINEATION IN THE COOPERATIVE GROUP SETTING

Purpose: Variations in target volume delineation represent a significant hurdle in clinical trials involving conformal radiotherapy. We sought to determine the effect of a consensus guideline-based visual atlas on contouring the target volumes.Methods and Materials: A representative case was contoured (Scan 1) by 14 physician observers and a reference expert with and without target volume delineation instructions derived from a proposed rectal cancer clinical trial involving conformal radiotherapy. The gross tumor volume (GTV), and two clinical target volumes (CTVA, including the internal iliac, presacral, and perirectal nodes, and CTVB, which included the external iliac nodes) were contoured. The observers were randomly assigned to receipt (Group A) or nonreceipt (Group B) of a consensus guideline and atlas for anorectal cancers and then instructed to recontour the same case/images (Scan 2). Observer variation was analyzed volumetrically using the conformation number (CN, where CN = 1 equals total agreement).Results: Of 14 evaluable contour sets (1 expert and 7 Group A and 6 Group B observers), greater agreement was found for the GTV (mean CN, 0.75) than for the CTVs (mean CN, 0.46-0.65). Atlas exposure for Group A led to significantly increased interobserver agreement for CTVA (mean initial CN, 0.68, after atlas use, 0.76; p = .03) and increased agreement with the expert reference (initial mean CN, 0.58; after atlas use, 0.69; p = .02). For the GTV and CTVB, neither the interobserver nor the expert agreement was altered after atlas exposure.Conclusion: Consensus guideline atlas implementation resulted in a detectable difference in interobserver agreement and a greater approximation of expert volumes for the CTVA but not for the GTV or CTVB in the specified case. Visual atlas inclusion should be considered as a feature in future clinical trials incorporating conformal RT. (C) 2011 Elsevier Inc.Biological, physical and clinical aspects of cancer treatment with ionising radiatio

Interplay between nuclear structure and reaction mechanism in the production of projectile-like short-lived isomers

Matière Nucléair

Low-energy Coulomb excitation of neutron-rich zinc isotopes

At the radioactive ion beam facility REX-ISOLDE, neutron-rich zinc isotopes were investigated using lowenergy Coulomb excitation. These experiments have resulted in B(E2, 2+1 → 0+1 ) values in 74−80Zn, B(E2, 4+1 → 2+1 ) values in 74,76Zn and the determination of the energy of the first excited 2+1 states in 78,80Zn. The zinc isotopes were produced by high-energy proton- (A = 74, 76, 80) and neutron- (A = 78) induced fission of 238U, combined with selective laser ionization and mass separation. The isobaric beam was postaccelerated by the REX linear accelerator and Coulomb excitation was induced on a thin secondary target, which was surrounded by the MINIBALL germanium detector array. In this work, it is shown how the selective laser ionization can be used to deal with the considerable isobaric beam contamination and howa reliable normalization of the experiment can be achieved. The results for zinc isotopes and the N = 50 isotones are compared to collective model predictions and state-of-the-art large-scale shell-model calculations, including a recent empirical residual interaction constructed to describe the present experimental data up to 2004 in this region of the nuclear chart

Coulomb Excitation of Neutron-Rich Zn Isotopes: First Observation of the 2+_1 State in 80Zn

Neutron-rich, radioactive Zn isotopes were investigated at the Radioactive Ion Beam facility REX-ISOLDE (CERN) using low-energy Coulomb excitation. The energy of the 2 state in 78Zn could be firmly established and for the first time the 2+0 transition in 80Zn was observed at 1492(1) keV. B(E2,20) values were extracted for 74,76,78,80Zn and compared to large scale shell model calculations. With only two protons outside the Z=28 proton core, 80Zn is the lightest N=50 isotone for which spectroscopic information has been obtained to date. Two sets of advanced shell model calculations reproduce the observed B(E2) systematics. The results for N=50 isotones indicate a good N=50 shell closure and a strong Z=28 proton core polarization. The new results serve as benchmarks to establish theoretical models, predicting the nuclear properties of the doubly magic nucleus 78Ni