tracking of low energy heavy ions
DESCRIPTION
Tracking of low energy heavy ions . Two applications in nuclear physics. Upstream beam tracking at medium energy (>10MeV/u) Downstream reaction product tracking at low energy (TRANSCRIPT
Antoine Drouart CEA Irfu/SPhN – [email protected] DITANET Conference 11.09 – 11.11.2011 – Sevilla
1/17
Two applications in nuclear physics
- Upstream beam tracking at medium energy (>10MeV/u)- Downstream reaction product tracking at low energy (<1MeV/u)- Event by event detection
Antoine Drouart CEA Irfu/SPhN – [email protected] DITANET Conference 11.09 – 11.11.2011 – Sevilla
2/17
Application : Upstream Tracking
unknown distribution
Incomingbeam
Target
θ1Scattering angleIncident angle
Position of vertexVelocity
θ0(x0,y0)
v0
perfect beamθ1
With a perfect beam track only the outgoing
particles
Large Beam emittance ~10π mm.mrad (hor+vert)
1.5m upstream 0.5m upstream On target
Antoine Drouart CEA Irfu/SPhN – [email protected] DITANET Conference 11.09 – 11.11.2011 – Sevilla
3/17
Effects on kinematics reconstruction
C. JOUANNE (SPHN) PHD 2002
11C+p 11C+p’ 40.6 MeV/u
11C 11C
ProtonEp
Θp
E*
WithoutBeam Tracking
WithBeam Tracking
Antoine Drouart CEA Irfu/SPhN – [email protected] DITANET Conference 11.09 – 11.11.2011 – Sevilla
4/17
Experimental set-up: CATS + MUST2
BEAM
2nd tracking detector
Target
7cm
MUST 2 : light particle detector (p, d, t, He, Li) (ΔE,E) or (E,t) : identification(x,y) : scatering angle
Antoine Drouart CEA Irfu/SPhN – [email protected] DITANET Conference 11.09 – 11.11.2011 – Sevilla
5/17
The CATS Beam Tracking DetectorsLow Pressure gas detector
Low pressure (P=4-10 Torr)gas: CF4, C3F8, iC4H10
Thin windowMylar 1.5µm
Anode
i+ i+ i+ i+ e- e- e- e-
cathodes
E If E/P high enough avalanche (>100V/cm/Torr) amplificationcharge movement induced signalelectrons are rapid fast signal
incoming ion
conducting Strips
Charge distribution positionX
10ns
600mV (after gain x200)
Antoine Drouart CEA Irfu/SPhN – [email protected] DITANET Conference 11.09 – 11.11.2011 – Sevilla
6/17
Basic CATS/BTD mechanics
Active area: 7x7cm2
iC4H10 @ 6Torr2x28 strips on cathodes1 fast anode signal
Ottini & al., NIM A, 431(1999) p. 476-484.
Antoine Drouart CEA Irfu/SPhN – [email protected] DITANET Conference 11.09 – 11.11.2011 – Sevilla
7/17
Virtues & Flaws of Low pressure detectors
- fast signal good time resolution σ = 100ps- good position resolution σ = 100µm- high detection efficiency (~100%)- large size available (>100cm2)- cheap and can be repaired- Thin : ~5µm of Mylar (from windows and cathodes)
- vulnerable to discharge : rate < 106pps- 1.5µm windows required Eion > 10MeV/u- fragile and delicate to use
Antoine Drouart CEA Irfu/SPhN – [email protected] DITANET Conference 11.09 – 11.11.2011 – Sevilla
8/17
Application : Downstream Tracking
Very low Energy regime <1MeV/u
The Super Separator Spectrometer S3
- Selection and transmission of low energy fusion-evaporation residues In flight mass measurement
Magnetic dipoleElectric dipole
Beam
Momentum achromat
Mass spectrometer
Final focal plane
Antoine Drouart CEA Irfu/SPhN – [email protected] DITANET Conference 11.09 – 11.11.2011 – Sevilla
9/17
Mass Dispersive Focal plane
Shashikant Manikonda, ANL
Momentum Achromat Mass Separator10cm
10cm
100Sn99Sn 101Sn
Q=24+ Q=23+ Q=22+Q=25+Q=26+
Distribution FWHM ~ 1.3 mm
Antoine Drouart CEA Irfu/SPhN – [email protected] DITANET Conference 11.09 – 11.11.2011 – Sevilla
10/17
Ions
Emissive foil(Mylar+Al, Carbon)
Secondaryelectrons
E
B
Electron detector = gaseous detector
Very low thickness< 1µm foil
Secondary emission- low energy electrons (few eV)- depends on the material (CsI…)- surface process- proportional to dE/dx
Emissive foil detector
Antoine Drouart CEA Irfu/SPhN – [email protected] DITANET Conference 11.09 – 11.11.2011 – Sevilla
11/17
The Se-D : Secondary electron Detector
Antoine Drouart CEA Irfu/SPhN – [email protected] DITANET Conference 11.09 – 11.11.2011 – Sevilla
12/17
The Se-D : Secondary electron Detector
Antoine Drouart CEA Irfu/SPhN – [email protected] DITANET Conference 11.09 – 11.11.2011 – Sevilla
13/17
Existing Se-D Detector
VAMOS Spectometer Focal plane size : 10 x 40 cm2
Magnetic coils
Metal testing Mask
Emissive foil
Secondary Electron Detector
Incoming ions
- <1µm of Mylar- σtime ~ 100ps- σspace ~ 600µm
Antoine Drouart CEA Irfu/SPhN – [email protected] DITANET Conference 11.09 – 11.11.2011 – Sevilla
14/17
Y cathode(wires)anode (wires)
X cathode(strips)
anode (wires)
X+Y 2D cathode (strips)
- similar time resolution σtime ~ 100ps- more robust- higher counting rate : up to 2.106pps
Se-D with one 2D cathode
Antoine Drouart CEA Irfu/SPhN – [email protected] DITANET Conference 11.09 – 11.11.2011 – Sevilla
15/17
SED2D sym. chamber of 201x138 mm2 or 68x47 1D strips - Mounted since sept 2011, time resolution on-going - AFTER-SED ASIC to connect- Spatial resolution to be done
New Prototype for S3
Antoine Drouart CEA Irfu/SPhN – [email protected] DITANET Conference 11.09 – 11.11.2011 – Sevilla
16/17
Conclusions & Perspectives
Upstream Beam Detectors: MWPC good time and position resolutionBUTLimited counting rate + not so thin (5µm of Mylar)
Downstream reaction product detectors: emissive foil MWPC as 1st generation 2D cathode placegood time resolution, very thin, high couting rate BUTpoor position resolution σspace ~ 600µm
To come- improve position resolution of emissive foil detector- test of other secondary electron detector : Micromegas use emissive foil detectors for upstream applications
Antoine Drouart CEA Irfu/SPhN – [email protected] DITANET Conference 11.09 – 11.11.2011 – Sevilla
17/17
People involved at CNA, GANIL and CEA/IRFUTechnical support & Engineering: T. Chaminade, F. Druillole, E. Monmarthe (IRFU) M. Kebbiri (IRFU), S. Damoy (GANIL), M. Riallot (IRFU), G. Fremont (GANIL)
Scientific coordinator : M. Alvarez (CNA), H. Savajols, E. Clement, F. Farget (GANIL), A. Drouart, D. Doré, T. Materna (IRFU)
Technical coordinator and analysis : B. Fernandez (CNA) , J. Pancin (GANIL), T. Papaevangleou (IRFU)And the others
Collaboration