GEMPIX detectors as hadron therapy beam monitors and radioactive waste detectors

J. Alozy, S. George , F.Murtas , M. Silari 1CERN 17-06-2014

GEMPIX detectors as hadron therapy beam monitors and radioactive

waste detectors

• GEMPIX construction• Beam monitor for Hadrotherapy• GEMPIX for Radioactive Waste• Conclusions

F.Murtas INFN-CERN-ArdentJ. Alozy, E.Frojdh, S. George , M. Silari CERN


Gempix Detector

Side view

Quad medipix board

The detector has two main parts :- The quad medipix without silicon sensors- The triple gem detector with HV filters and connector

New HV GEM board


Gem foils and frames A new GEM layout has been designedActive area of 28x28 mm2 The electordes path have been designed to avoid the medipix wire bonding.Produced by Rui De Oliveira.

New frames were designed 10x10 cm2

to fit the holes of the Quadmedipix board

5 different thickness (from 1 to 5 mm)

Wire bonding position


Assembling the GEM foils

The three GEM foils are assembled on top of HV GEM board


Final detector


Head on detector

Gas flux AR CO2 or AR CO2 CF4

The anode is a quad naked without silicon sensor :The active area is 9 cm2

Triple GEMMylar window

Particles to be analysed

HVGEM Console

FITPIX Console

HV

FITPIX


A small TPC

Gas fluxThe anode is a quad medipix without silicon sensor:The active area is 9 cm2

The particle track is analysed with 512 pixel in length of 3 cm

This detector could be used also as Tissue Equivalent Proportional Chamber The track path is equivalent to 30 microns of tissue … with 17 samples/microns

Triple GEM

Kapton windowParticles to be analysed

Length analysed


GEMPIX Detectors

Head-on version(4 detectors)

Side-on version(2 detectors )

HV Connector

MedipixDAQ box


Measurements atCNAO (Pavia - Italy)Carbon ion beam

at 480 Mev/nucleon


MeasurementsBeam : 480 MeV/A Carbon Ion

Measurements in air

Measurements in water phantom :23 different depths throughout water phantomEach position given spot 5.108 carbon ion treatment (clinical treatment intensities)

Frame length = 1ms, gas = ArCO2, gain = 750 V (~0.43 keV/TOT - Proper calibration awaits the return of the detector from CNAO RP).


Mylar windowGas in/out

Fitpix Readout

External HV (HVGEM)

GEMPIX at CNAO (Pavia)


GEMPIX as a Beam Monitor

480 MeV/A carbon ions, 10 ms frame, ASIC in Medipix (particle counting) Mode, IKrum = 5

Counts

Single Carbon Ion

Other particle


The overall beam shape is clearly visible

Beam profile

As number of hits As energy released


Gempix Linearity

Number of counts per spills

Time (s)


Phantom used at CNAO

Bragg Peak finder at CNAO

Thin WindowGempix

Stepper Motor

Several measurement of energy deposition along the beam (5x108 Carbon ions per 10 spills)


Energy deposition is ~0.43 keV/TOT Spot width here is sigma of gaussian (FWHM = 2.3 sigma)

Depth profile and beam dimension


Linear Log 3D reconstruction

Energy deposition: 3D reconstruction

This part (neutrons and gammas) could be analyzed with really high resolution


Single Event Upset

Depth = 124 mm (in bragg peak), ~0.43 keV/Count (9.6 MHz, TOT mode), IKrum = 1, 1ms frame

SEU Events


No Cfg Resets

Reset at start

Reset/10 frames

Reset every frame

Reconfiguring


Radioactive Waste :a detector for 55Fe


Sample Preparation

Fraiseuse DECKEL FP4M for powder productionreducing the 60CO background

Boxes supplied by SMIPA s.r.lDimension: 38x38x4 mm3

(now 38x38x8 mm3)Weight: 3.951 ± 0.15%

Measurements for Fe-55 concentration with GEMPIX ,two different configuration :Drift gap 11 mmDrift gap 3 mm

Support conceived for measurements with samples and calibration sources


Radioactive waste: 55Fe

1 sec radioactive source

100s counts


X-ray candidates

Bck

Signal vs Background

Gas AR CO2CF4Gate: 1 sHV 1200 VGas flux: 3.5 l/h

Clk: 24Ikrum: 5Polarization: -


Cluster parameters measurements

Cluster type Cluster volume Inner size

Border size Size Size y vs size x

55Fe

60Co

55Fe

60Co

55Fe

60Co

55Fe

60Co

55Fe

60Co


Online analysis

Once that the calibration values are set in the Python script, an online analysis can be performed

Number of X-Rays measured in 1000 sec

Number of big blob

Cut on sizeCut on charge


Drift 3 mm vs drift 11 mm

Attenuation length 2.91 cm

Theory: 11 mm/ 3 mm = 2.6

Measurements:11 mm/ 3 mm = 2.7

Waiting the measurements from certificated company for the final calibration


Summary Six GEMpix detectors have been built and they show good performances

from single particle detections to high intensity beam monitor

Really good cluster analysis is possible thanks to the Fitpix software pakage

Software tools and detector tuning are still needed for the cluster analysis in gas (dE/dX, particle id, 3D track reconstruction....)

The detector could be easily improved with Timepix3 chips

Other applications and measurements are scheduled for next months Monitor for burning plasma (KSTAR - PETAL) Measurements for micro and nano dosimetry with tissue equivalent gasMonitor for gamma radiotherapy

Documents

GEMPIX detectors as hadron therapy beam monitors and radioactive waste detectors