Task10 : Physics & Instrumentation Subtask: Single Particle & Collective Properties( Contributors: Angela Bonaccorso, Roy Lemmon, Valerie Lapoux, Yorick Blumenfeld.) • Check limits of validity of mean field and single particle concepts for medium to heavy mass nuclei with exotic Z/N and particle separation energy Sn ~10 MeV. Also the long range and short range correlations can vary, as a consequence of the isospin dependence of the N-N interaction. • Study interior part of wave functions of nucleons and clusters. • Un example of study of new reaction mechanisms: Full kinematics reconstruction deep inelastic experiments.
I. Full kinematics reconstruction slightly deep inelastic experiment Heavy target (208Pb), medium mass neutron rich projectile (A=30-60). Measure knockout (nuclear breakup) of neutron, proton and a. Projetile and target g-rays plus neutrons from the target to reconstruct excitation energy. Check peripherality of the reaction by impact parameter identification via angle measurement (semiclassical system, large Sommerfeld paramether) in an event by event reconstruction. Width of core momentum distribution larger for smaller (core-target) impact parameters. Reduction of spectroscopic factors values and of ANC ?
R.Lemmon Daresbury Laboratory, UK. • II. One-proton removal reactions and (d,3He) transfer reactions using beams of neutron-rich Pb isotopes from EURISOL will consitute another key experiment within this programme. Explore how the spectroscopic factors and occupancy of the 3s1/2 proton orbital changes in the heavy neutron-rich Pb isotopes.
R.Lemmon Daresbury Laboratory, UK. III: Instrumentation
EURISOL 82 50 50 40 132-140...Sn 20 82 28 EURISOL 70 ? 20 110Zr 78Ni 8 2 8 neutron drip-line known up to Z=8 (24O)… 28 2 Explorations of the nuclear landscape using EURISOL beams doubly magic stable nuclei drip-lines & properties in the vicinity of new doubly magic nuclei ? Nuclear densities ? Halo shapes ? doubly magic unstable nuclei? TYPICAL EXPERIMENTS : 34-38Ne(p,p’) (p,d) (p,t) (d,3He) 78Ni(p,p’) (N=50) 60-70Ca (N=40,50) 104Se (Z=34, N=70) . V. Lapoux CEA-Saclay DSM/DAPNIA/SPhN
6He(p,p’) @40.9 A.MeV Ganil /SISSI MUST data S2n = 0.975 A. Lagoyannis et al., PLB 518 (2001) 27 6He(p,p) rms = 2.5 0.1 fm 8He 5-body density 6He(p,p’)6He(2+) 2+ 1.8 MeV 6He 3-body density 0+ 6He >>> Specific tools to study unbound states of weakly-bound nuclei: direct reactions in inverse kinematics and missing mass method Tool to probe proton and neutron densities: (p,p’) scattering Elastic scattering sensitive to the matter rms Inelastic scattering : sensitive to the shape of the density distribution (p,p) not enough for testing radial shapes of densities, through (p,p’) we obtain not only excitation but also features of the density profiles . V. Lapoux CEA-Saclay DSM/DAPNIA/SPhN
Z N Skin and halos Soft collective modes (d,3He) (d,2p) reactions Knock-out Going closer to driplines with higher intensities: openes new physics fields EURISOL GOALS : Structure and spectroscopy close to or at the drip-lines BEAMS INFORMATION PROBES Neutron-rich isotopes close to the drip-lines: 24O, 30Ne (p,p’) Required intensities I > 103 /s Spectroscopy Low-lying states Chains O (24O), Ne + Mg, Si, S, Ar : we need to complete the studies of the neutron excitation done for the 1st generation of RIBS Evolution of neutron excitation Mn vs Nalong isotopic chains (p,p’) on a wide angular range Required intensities I > 104 /s Ex : 34,36Ne, 38Ne (if not unbound), 60-70Ca, 78Ni 104Se (Z=34, N=70) Exotic shapes and densities spectroscopy of neutron-rich around magic numbers N=28, N=40 (new possible magic) N=50, N=70 (new) One-particle state Spectroscopic factors . V. Lapoux CEA-Saclay DSM/DAPNIA/SPhN
Detection for EURISOL experiments At the drip-lines : Low Sn, S2n, S4n, (below 10MeV) : most of the excited states are unbound Phase space background due to neutrons produced by decaying unbound states 78Ni(p,p’)78Ni* + AZ IDof forward focused heavy fragments : Spectrometer or SiLi, CSI arrays close to targets ? + neutron detection 78Ni +p p’ + 78Ni* p + 76Ni + 2n p’ +78Ni* p + 74Ni + 4n 78Ni(p,d)77Ni 78Ni +p d + 77Ni unbound? d + 76Ni + n d +77Ni* d + 74Ni + 3n Check: alpha-neutrons correlations Needs LCP and neutron devices granularity & efficiency 78Ni(p,t)76Ni 78Ni +p t + 76Ni t + 76Ni* t + 75Ni* + n t + 74Ni + 2n ID, E vs Theta of LCP . V. Lapoux CEA-Saclay DSM/DAPNIA/SPhN
Improved detection for EURISOL experiments 2016 Wishes for Coupled Detection devices • Charged-Particle spectroscopy • needed to exploreunbound states • Thin light targets p, d • DE ~ 400keV to 1 MeV • (p,p’), (p,d) (p,t) • + • Inverse kinematics : • good Energy resolution in Eexc • requires : beam profile on target • beam tracking detectors + • Gamma-ray spectroscopy • needed to separate close excited states • Thick target DE ~ 20keV Steps beyond in the detection : - ASIC technology (Application Specific Integrated Circuit) (compacity of all devices) - Mixed detection (gamma+ charged particles +… neutrons) : Ex : Ge + Si + scintillator in a crystal-Ge-Si ball array -Higher multiplicities in LCP arrays (3,4,..) challenges in acquisition systems : synchronize separated arrays & triggers needs to reduce dead time + A,Z ID of heavy fragment in a spectrometer or SiLi CsI array + NEUTRON DETECTION . V. Lapoux CEA-Saclay DSM/DAPNIA/SPhN
structure of drip-line nuclei Complete set-up for direct reactions on proton and deuton targets Means BEAMS OF RARE ISOTOPES Today 1/s, EURISOL 103-105 /s Means DIRECT PROBES i.e p & d targets, + Polarized p,d DIRECT REACTIONS Einc ~ 20-50 MeV/n Nearly (~90%) pure beam target: CH2 orcryogenic H2 exotic beam AZ p identification EURISOL A+1Z Beam Tracking Devices BTD -ray detection: future AGATA Light charged particle (LCP) detection . V. Lapoux CEA-Saclay DSM/DAPNIA/SPhN
CONCLUSION FROM THE ISGMR Fully self-consistent calculations of the ISGMR using Skyrme forces lead to K∞~ 230-240 MeV. Relativistic mean field (RMF) plus RPA: lower limit for K∞ equal to 250 MeV. It is possible to build bona fide Skyrme forces so that the incompressibility is close to the relativistic value. → K∞ = 240 ± 10 MeV. To reduce this uncertainity one should fix the density dependence of the symmetry energy. COLO, Trento
Detection constraints • GMR must be measured around 0 deg. in the CM frame • Needs for a high efficiency detector • With low energy threshold • GQR contribution is evaluated from larger qCM angles and subtracted • Test the detection setup on 56Ni : heaviest N=Z nuclei ever studied for the GMR 0 4 6 8 10 2 qCM(deg.)
Kinematics 56Ni(a,a’) at 33MeV/u GMR GQR ,5
The MAYA detector • 4p solid angle coverage • Low energy threshold (~200 keV) • Thick gazous He target (28 cm) a • Measure the angle and the energy of the recoiling a by trajectory reconstruction • Suppression of the beam signal with two plates around the beam • Resolution : 50 keV in energy • 4° lab angle R&D : ACTAR JRA (EURONS)
GRAPA • R&D on charged particle • detectors • Detectors • Electronics • Data Acquisition
Developments necessary… • Improvements of PSD performance through nTD Si, with segmentation. • Development of 5cm thick planar segmented Ge detectors; mounting of Si-Ge telescope with minimum dead layers. • Explore alternatives to Ge (CdZnTe…) • ASIC Electronics • High dynamic range preamplifiers • CFDs • Fast digital pulse sampling • Cryogenic H and He targets; polarized targets