Title: Title
Author: Philippe CHOMAZ
Last saved by: Administrateur
Company: GANIL

Mapping of Single Particle Energies using Transfer Reactions.

Abstract  
Single particle energies can be mapped out using one-nucleon transfer reactions such as (d,p) or (p,d). This is the most direct way of measuring shell gaps far from stability and assessing the modification of magic numbers. A very efficient set-up for particle-gamma coincidences needs to be built.
Keywords 
Single particle energies, shell gaps, magic numbers, transfer reactions, particle gamma coincidences, Si strip and germanium detectors.

Physics case
 	Shell gaps and shell ordering are expected to change when moving far from stability. Following their evolution is a major subject of Radioactive Beam physics, both today and in the future when more exotic nuclei will become accessible. 
Observable
One nucleon transfer reactions such as (p,d) and (d,p) provide a direct measurement of single particle energies as long as a large fraction of the spectroscopic strength is observed.   The observables are the excitation energies, angular distributions and hopefully analyzing powers of all the levels populated. Such measurements give more precise information than indirect approaches such as mass measurements, 2^+ energies etc…, but larger beam intensities are necessary. 

Proposed experiment
	The experiments are performed in inverse kinematics where the radioactive beam impinges the target containing the probe, possibly plastic (CH_2 or CD_2) or preferably pure hydrogen or deuterium. Polarized targets would allow for very interesting analyzing power measurements, distinguishing between J=l+1/2 and J=l-1/2 orbitals. The kinematics of the reaction (excitation energy and scattering angle) are determined from the angle and energy measurements of the recoiling light particle. Detection of the scattered projectile-like nucleus provides channel selection. In many cases an efficient coincident gamma-ray measurement is necessary to overcome the limited energy resolution of the particle detection. 
Requirements:
Beam properties
Beam between 10 AMeV for (d,p) and 30 AMeV for (p,d). with an intensity of at least a few 10^3 pps. Availability of isotopic and isobaric chains. Beam spot of 1-2 mm diameter would avoid the tedious beam tracking routine. Beam energy resolution not crucial. Time resolution better than 1ns. 

Detection
	Combined 4π particle-gamma array such as GRAPA described in detail the EURISOL RTD report (Appendix 5, section 5.2) is the ideal set-up specifically designed for such experiments, and possibly not so futuristic considering the EURISOL time-scale. Any watered down GRAPA (2π particle combined with 2π gamma detection or gamma detection with scintillators) would be adequate for many cases. 
Theoretical support
Improvement of effective interactions and mean field and shell model calculations far from stability as well as improved direct reaction calculations and optical potentials would be nice. But the experiments are of intrinsic interest and current reaction models are probably adequate for a first analysis.