1. The DESIR facility at SPIRAL2
DESIR: Désintégration, excitation et stockage d’ions radioactifs
(Decay, excitation and storage of radioactive ions)
Informal collaboration to promote ISOL beams at SPIRAL2
Result of a SPIRAL2 workshop in July 2005 on ISOL beams at SPIRAL2:
- beam handling and beam preparation
- LASER spectroscopy
- Decay spectroscopy
Spokes-person: B. Blank
GANIL liaison: J.-C. Thomas
Bertram Blank, NUSTAR meeting, february 2006

2. Objectives Traps for beam preparation and trap assisted spectroscopy
Setups for laser spectroscopy: Collinear laser spectroscopy and b-NMR
 moments, spins, radii etc.
Setups to study fundamental interactions:
 CVC, CKM matrix: 0+ → 0+ transitions
 exotic interactions like scalar or tensor currents
MOT trap: electric dipole moments to test CP violation and T violation e.g. with Ra
Laser PAUL trap: high-precision magnetic and quadruole moments, radii, spins
Decay spectroscopy: p-p correlation, astrophysics, cluster emission, GT strength
exotic shapes, halo nuclei etc.
solide state phyics and other « applications »

3. SPIRAL 2 LAYOUT
GANIL facility
LIRAT
LINAG
Production building
DESIR

4. Conclusions of the SPIRAL2 Workshop (july 2005)
Low energy RIB
1. A new experimental area of about 1500m2 located at the ground floor, dedicated for the experiments with low-energy beams from SPIRAL2 is strongly requested. The new building includes area for the experimental equipments, acquisition and control rooms.
2. A High Resolution mass Separator (HRS) with a resolution of M/M>5000 with a dedicated identification station is absolutely necessary. A separation scheme Low Resolution mass separator → RFQ cooler → HRS is proposed.
3. The low energy radioactive beams should be available for experiments already in the beginning of the operation of SPIRAL 2. The physics program would require both neutron-rich and neutron-deficient beams.
4. More than one production target – ion source station is required to ensure flexible schedule and a possibility for fast change of the mass of radioactive beam.
5. An extension of the current LIRAT beam line in order to take a full benefit of the SPIRAL 1 beams is proposed.

5. SPIRAL ISOL : IBE + LIRAT
Station IBE

6. Possible extension of LIRAT
Multi-beam capabilities (physics program  2011)
Tests and development for SPIRAL2 & DESIR
LIRAT actuel
Spec. b
LPC Trap ?

7. Underground
J.-C. Thomas

8. Possible extension of LIRAT
Multi-beam capabilities (physics program  2011)
Tests and development for SPIRAL2 & DESIR
LIRAT actuel
SPIRAL2 1+ n+
Spec. b
LPC Trap ?
J.-C. Thomas

9. Spectroscopy of trapped beams Fundamental Interactions
Ground-floor
Laser Spectroscopy
Spectroscopy of trapped beams
Decay studies
Other purposes
Cooling/Bunching
Fundamental Interactions
J.-C. Thomas

10. Search for exotic interactions
b-n angular correlation
requires to measure the recoil ion
within the SM
x : Fermi fraction; r : GT/F mixing ratio
beyond the SM
a contains quadratic S and T contributions
O. Naviliat-Cuncic et al., LPC Caen

11. Production and preparation of 6He
candidate:
(pure GT transition)
deduce bn correlation from measurement of b-recoil
(recoil with very low energies < 1 keV)
6He+ production at SPIRAL
cooling in H2 gas / bunching
trapping/measuring
LIRAT low energy beam line
O. Naviliat-Cuncic et al., LPC Caen

12. Setup and first results
TOF of ions extracted from trap
mCP recoil ion detector
beta telescope PM
plastic scintillator
DSSSD
beam
monitor
mCP
6He+
10cm
first b-decay detection
RF ON/OFF
(V-A theory)
O. Naviliat-Cuncic et al., LPC Caen

13. Search for p-p correlation in b2p decay
Two possible decay schemes:
sequential → no angular or energy correlation
2He type decay → angular and energy correlation
 pairing correlations, nucleon-nucleon interaction….
Possible candidates:
22Al, 23SI, 26P, 27S, 31Ar, 35Ca, 43Cr, 50Ni ….
Setup:
6 DSSSD
6 large-area
silicon det.
g detection
beam catcher
I. Matea et al., CEN Bordeaux-Gradignan

14. 6 E detectors (b rejection) 3 EXOGAM germanium detectors
The setup:
Silicon cube
6 DSSSD detectors
( ~75% efficiency)
6 E detectors (b rejection)
3 EXOGAM germanium detectors
Removable catcher
I. Matea et al., CEN Bordeaux-Gradignan

15. Study of decay of 31Ar at LIRAT/IBE
Proton spectrum
Production rate: – Ar per second
strong contamination from 33Ar
I. Matea et al., CEN Bordeaux-Gradignan

16. b-NMR at DESIR Applicable to many cases, in particular to light nuclei
G. Neyens et al.

17. Collinear laser spectroscopy and b-NMR
F.Leblanc et al.
G. Neyens et al.
charge radii from isotope shifts (center of gravity)
HFS gives magnetic moments (g*I) and Q moments
in some cases, one can extract spin
b-NMR: g factor and, with HFS, one gets spin

18. Open to everyone interested
Synergies with FAIR/NuSTAR
Beam preparation: cooler, traps,
trap-assisted spectroscopy (MATS)
Laser setups (LASPEC)
Neutron detection (NCAP)
New types of charged-particle and gamma detectors (e.g. LaBr2)
Low-energy beam diagnostics
…….
To a large extent the same community!!!!
B. Blank, M.J.G. Borge, P. Cambell, F. Herfurth, A. Jokinen, F. Leblanc, M. Lewitowicz,
D. Lunney, O. Naviliat-Cuncic, G. Neyens, J.C. Thomas and many more…
Open to everyone interested

20. Wien Filter separator Exp. Hall HRS Ident. CIME n+ 1+ LIRAT beam
J.-C. Thomas

21. SPIRAL2 mass separator review October 2005
Panel Members: Remy Anne, Paul Berkvens, Pierre Bricault (Reporter), Richard Catherall, Tim Giles (absent), Alex Mueller (SPIRAL 2 TAC Chair), André Tkatchenko and Martin Winkler
Mandate: Expertise on 3 options (Wien Filter, Brama type and ”Bi-selective”) for the low resolution two-beam mass separator
Recommendations:
The “Wien filter” approach seems better only because we lack information regarding the use of large beam intensity in electrostatic lenses and the detail of the beam transport between the Wien filter and the mass separator
One other option proposed by Remy Anne (during the meeting), in this option the beam from the source is separated in space by a septum and then two beams are produced.
On the other hand if this beam splitting appears not viable or one find this is not acceptable to reduce the intensity for the experiment and considering the cost associated with each proposed solution one can consider the addition of a second target station. The primary beam can easily be shared between the two stations using pulsed magnet.