1. Jose Javier Valiente Dobón LNL (INFN)
Ancillary devices for spectroscopy with Quasi-Elastic and Deep-Inelastic Collisions.
Jose Javier Valiente Dobón
LNL (INFN)

2. Overview Need of an ancillary heavy ion detector.
Ancillary detectors based on PPACs.
The Pyramid, Liverpool-Daresbury and CHICO detectors.
The new DANTE array at LNL.
An ancillary heavy ion detector for SPIRAL2
Summary.

3. Requirements of a heavy ion detector
Need of Heavy Ion Detectors
Detection of scattering angles  determine reaction kinematics
Heavy-ion γ-ray coincidence  Doppler correction event-by-event basis
Requirements of a heavy ion detector
Resistant to radiation damage
Minimize absorption losses
Good position resolution
Small dimension γ
TLF
BLF
Beam
Target
HPGe θ

4. Ancillary detectors based on PPACs
Trapezoidal form to maximize solid angle, Ω=1.8π
Constant gas flow of isobutane
Resistive cathode made of low absorption material
Position Resolution ∆Θ=∆φ= 1-2o
Pyramid
Liverpool-Daresbury
One annular backscatter detector
Six trapezoidal forward detectors
Constant gas flow of isobutane
Small γ attenuation
Resolution ∆Θ=1o, ∆φ=10o (forward)
K. Vetter et al., NIM A344, 607 (1994).
A.J. Cresswell et al., PRC51, 1025 (1995).

5. Gammasphere
Beam
CHICO
Beam
Target
Rates 100 k/s
Trapezoidal form, 10 azimuthal sections. Solid angle Ω=2.7π
Segmented delay-line cathodes
Segmented anodes asymmetrically
Position Resolution: ∆θ=10, ∆φ=90
TOF resolution 500ps; Δm/m=5%
M.W. Simon et al., NIM A452, 205 (2000).

6. Fragment Identification
Position determination
Fragment Identification
Segmented asymmetrically
198Pt + 850MeV LBNL
Coincidence two co-planar anode pairs (resolution φ=90):
Large-Large
Large-Small
Small-Large

7. Doppler corrected γ spectra for TLF
Spectra Os isotopes, gated on Ba isotopes (binary partners).

8. PRISMA: Large acceptance Magnetic Spectrometer
CLARA-PRISMA setup
Quadrupole
Dipole
Start detector
X-Y, time IC
6m (TOF)
G.Montagnoli et al. LNL annual Report 165 (2000).
Position sensitive MCP
E-ΔE
MWPPAC
X-Y, time
ΔΩ = 80 msr ΔZ/Z  1/60 (Measured) ΔA/A  1/190 (Measured) Energy acceptance ±20% Bρ = 1.2 T.m
Angular range 30o o
PRISMA: Large acceptance Magnetic Spectrometer

9. 25 Euroball Clover detectors
CLARA setup
PRISMA-CLARA results
505 MeV (Θgrazing=64o)
Gate on 80As
(-1p -1n)
Level scheme from a thick
target GASP exp.
460 MeV 82Se on 192Os
Nucleus completely
unknown previously!
Reaction Chamber
25 Euroball Clover detectors
Efficiency~3%

10. DANTE (Detector Array for multi Nucleon Transfer Ejectiles)
Start detector of PRISMA  No possible to place PPACs
Limited efficiency of the PRISMA-CLARA setup  No γ-γ coincidences.
DANTE (heavy ion detector based on MCP) reveals the position interaction of the recoils  Doppler correction.
DANTE placed at the grazing angle, has a high efficiency  γ-γ coincidences  No need of an extra GASP experiment to build up a level scheme.
20°
Versatile
Beam
CLARA
PRISMA
MCP (50x70mm) detectors
Grazing angle
70°

11. First prototype of DANTE
Thickness:13mm
Preamplifier in vacuum
Linea di ritardo
MCP
Lateral section of the first DANTE prototype
Delay line

12. Test of the first DANTE prototype
Time resolution 130ps (TAC-ADC)
Position resolution <1mm
Sustained high counting rated
High noise rejection
TOF
X coordinate
Y coordinate
Amplitude

13. Heavy ion detector MCP based
An ancillary heavy ion detector for SPIRAL2
The selection of the ancillary detector will depend on the spectrometer chosen for SPIRAL2
Heavy ion detector MCP based
Radiation damage warranty: at least 1000 h under beam
Different geometrical forms of the MCP in order to cover the Ω=4π
Good performance: Position resolution and TOF
Mass resolution for light fragments through kinematic coincidences (e.g. A ≤ 20)
Relative low cost

14. Summary Some examples of heavy ion detectors based on PPACs :
Pyramid, Liverpool-Daresbury and CHICO.
DANTE array (MCP based detector) for the CLARA-PRISMA setup at LNL.
Possible use of DANTE like detectors in the radioactive beam facility, SPIRAL2.

15. CLARA-PRISMA setup
PRISMA
A & Z identification
“in-beam” γ-ray
CLARA