Mosaic Detector:
Experiments for Therapy and Space Research
R.Pleskac
GSI / Biophysics
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
Overview
Hadrontherapy & Space Research
 Significance of nuclear fragmentation
 Cave A measurements
(Bragg curves, nuclear fragmentation, microdosimetry, beam widening)
 FIRST experiment
(double-differential cross-section for Z particles)
Mosaic Detector
 Requirements
 Design
 Time Line
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
Significance of nuclear fragmentation
in RT with light ions
High-energy carbon beam stopping in water
I. Pshenichnov
Exp.
Investigations
(physical characterization)
Nuclear
fragmentation
–
–
–
LBLLoss
Berkeley
Ne 670
1970’s W. Schimmerling

of primary
ionsMeV/u
 depth-dose,
RBE
NIRS/HIMAC Chiba C, light ions
1990’s T. Kanai
Total reaction cross
section1990’s
1-2 b
GSI Biophysics
C, light ions
Carbon ion therapy
100-400 MeV/u
 Buildup of secondary fragments  dose-tail, lateral dose
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
Before treatment
Definition and delineation of target volume (CT,MRI,PET)
transform patient CT-data to water-equivalent
path length of ions
Treatment planning:
- find best entrance ports
- optimization (absorbed dose [Gy])
physical model
- biological optim. (RBE (LET(Z,E),dose …) [GyE])
Verify dose distribution in water phantom
(tolerable deviation < 5%)
Patient positioning
Patient treatment
R.Pleskac
Bragg curves +
fragmentation data
1st ADAMAS Workshop, GSI, 2012
18/12/2012
Precision Bragg curve measurements
The present data base includes
precise B.P. position data for
p, 3He, 7Li, 12C, 16O
Mechanical accuracy:
1 μm for relative thickness
0.1 mm absolute
Comparison of absolute B.P. positions
measured at GSI and HIT synchrotrons at the
same nominal beam energies:
→ agreement within < 2 ‰ rel. deviation
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
Bragg curves of 12C water
peak-width and height are affected by
– straggling
– fragmentation
increasing tail dose
© D.Schardt
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
Microdosimetry in-phantom measurements
Tissue-equivalent proportional chamber (TEPC)
Sensitive volume
120 mb TE-gas
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
Beam Widening –
- Film Stack in Water Acquarium
Stack of films placed in the waterphantom aligned with the beam axis
Irradiated GaF Chromic films
Photo© G.Martino
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
Fragmentation studies
- Fragment buildup in thick targets
- Neutrons
- Microdosimetry
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
Fragmentation Setup
The ΔE–E telescope detector
Angular distribution setup
→ Beam energy of 120 MeV/u
→ Cylindrical water target (diameter of 150 mm)
→ Telescope positionned at 0°, 20°, 30°, 60°, 90°
and 120°
R.Pleskac
Loss of primary ions setup
→ beam energy of 300 MeV/u
→ Target: 0, 1, …, 7 large water flasks
→ Telescope positionned at 0°
1st ADAMAS Workshop, GSI, 2012
18/12/2012
Signal processing & Data Acquisition (DAQ) system
Number of primary ions N0
→ big ionization chamber
Number of fragments N
→ ΔE-E telescope
Trigger
→ START and/or BaF2 detector
DAQ
→ GSI Multi Branch System (MBS)
→ Aug 2007 – CAMAC CVC based DAQ
→ Feb 2009 – CAMAC GTBC based DAQ
→ Aug 2012 – VME based DAQ
RAW DATA
→ List Mode Data (LMD) files
DATA ANALYSIS
→ on event-by-event basis
→ ROOT program (online / offline)
→ ΔE-E scatter plot → "banana" cuts →
identification of fragments
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
Identification of Fragments
E (BaF2)
7Li
at 120 MeV/u: ΔE-E scatter plot
4He
t
3He
d
γ+n
p
ΔE (plastic)
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
Loss of primary ions and fragment buildup
Loss of carbon Ions by
nuclear reactions
Buildup of secondary fragments
Surviving fraction
E. Haettner et al., GSI 2005
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
Spectral data
Fragment energy spectra 4mm behind B.P.
Buildup of secondary
fragments
E0 12C
He energy spectra at angles 0° - 6°
Comparison with
PHITS-code
E. Haettner et al., GSI 2005
E0 12C
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
FIRST – experimental setup in cave C
→ Beam diagnostics
→ New detectors in interaction region (IR)
Measurable
→ ALADIN dipole
→ Double-differential cross-section for Z particles
→ MUSIC + ToF Wall
→ LAND
Experiment in August 2011
(carbon beam fragmented on thick targets)
→ C + C (5 mm) at 400 MeV/u
→ C + Au (0.5 mm) at 400 MeV/u
→ coincidence measurement
→ on event-by-event basis
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
IR – START scintillator
IR – Beam Monitor
IR – Target
IR – Si Pixel Vertex Detector
IR- KENTROS
ALADIN Magnet
TP-MUSIC IV
TOF wall
LAND
18/12/2012
Future Experiments at GSI: Irradiation facilities
E = 0.1 – 2 GeV/u
E < 15 MeV/u
Cave C
FIRST experiment
Medical cave
Cave A
Fragmentation Experiments
Space research
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
Cave B (rear part)
Preparation of FIRST
18/12/2012
Mosaic Detector
new GSI mosaic detector
(based on n_ToF design)
n_ToF mosaic detector
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
Requirements / Geometry
Purpose:
 Beam monitor (counter) + START/STOP for ToF + Energy loss
 Particles: protons – carbon – iron - HI
 Intensities: 1e0 – 1e8/sec
(replacing existing START plastic scintillator)
sCVD:
 4,5 x 4,5 mm2 x 300 μm
 active area 4,0 x 4,0 mm2 (~ 80 % of total area)
Mosaic detector:
 3 x 3 sCVD
 total area 13,5 x 13,5 mm2 (beam spot 5 – 10 mm FWHM)
 9 x C2 + 1 x C6 preamplifiers
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
Characteristics
Signals
 protons - oxygen at 500 MeV: → 3.2 – 350 fC
 3.2 fC / 4 ns = 0.8 μA → 0.8 μA * 50 Ω = 40 μV
 40 dB current amplifier (f = 100) → 40 μV * 100 = 4 mV
 protons: S/B = 4 mV / 2.5 mV = 1.6
 oxygen: S/B = 200 mV / 3.2 mV = 62.5
 protons: using quick charge amplifier (4 mV/fC) → 3.2 fC * 4 mV/fC = 12.8 mV
→ S/B = 12.8 mV / 0.6 mV (noice) = 21.3
Time Resolution
 case of 16O: 1 ns / 100 ps = 10 ps
 case of protons: 3.5 ns / 21.3 ns = 150 ps
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
Proton / Carbon Interaction
Ionization for protons at 200 – 500 MeV
Ionization for carbon at 1 – 10 GeV →
150 – 600 fC (150 – 600 MIP)
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
n_ToF PCB Design (1)
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
n_ToF PCB Design (2)
Top layer
Bottom layer
Readout lines
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
Time line
 January 2013 – assembling
 February 2013 – final testing
 End of February 2013 - delivering
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012
THANK YOU FOR YOUR ATTENTION !
R.Pleskac
1st ADAMAS Workshop, GSI, 2012
18/12/2012