Energy calibration of the threshold of Medipix for ATLAS
description
Transcript of Energy calibration of the threshold of Medipix for ATLAS
![Page 1: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/1.jpg)
Energy calibration of the threshold Energy calibration of the threshold of Medipix for ATLASof Medipix for ATLAS
Céline LebelUniversité de Montréal
presenting for the
Institut of Experimental and Applied Physics
of the Czech Technical University in Prague
Charles University - April 5th2007
![Page 2: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/2.jpg)
C. Lebel 2 / 52
People involved in this projectPeople involved in this project• Institut of Experimental and Applied Physics of
the Czech Technical University in Prague – Stanislav Pospíšil– Jan Jakůbek– Josef Uher– Vlastimil Král– Michal Platkevič– Vladimír Tichý
• Charles University– Michal Suk– …
• Université de Montréal– Claude Leroy– Céline Lebel
![Page 3: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/3.jpg)
C. Lebel 3 / 52
OutlineOutline• Medipix
• Medipix in ATLAS: challenges foreseen
• Energy calibration of the low threshold– Equalization– Photons: Decreasing Flux– Alphas– Electrons– Neutrons
• Summary and Outlook
![Page 4: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/4.jpg)
C. Lebel 4 / 52
Medipix2 Medipix2 devicedevice - a single X-ray - a single X-ray photon counting pixel detectorphoton counting pixel detector
Medipix2Pixels: 256 x 256Pixel size: 55 x 55 μm2
Area: 1.5 x 1.5 cm2
Medipix2 QuadPixels: 512 x 512Pixel size: 55 x 55 μm2
Area: 3 x 3 cm2
• Planar pixellated detector (Si, GaAs, CdTe, thickness: 300/700/1000mm)
• Bump-bonded to Medipix readout chip containing in each pixel cell:
- amplifier, - double discriminator- and counter
Detector chip
Medipix chip
Bump-bonding
![Page 5: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/5.jpg)
ATLASATLAS
![Page 6: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/6.jpg)
C. Lebel 6 / 52
LHCLHC
![Page 7: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/7.jpg)
C. Lebel 7 / 52
ATLASATLAS
Height: 22mWidth: 44 m
Weight: 7000 tons
![Page 8: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/8.jpg)
C. Lebel 8 / 52
Medipix in ATLAS: the challengeMedipix in ATLAS: the challenge
• ATLAS environment has high radiation fluxes• Problem: is the device radiation hard?
– We don’t know.
• The data acquisition must be optimized to obtain the maximum information in the shortest maximum information in the shortest timetime.
• What kind of information are we looking for?– Composition and spectroscopic characteristics of
the radiation field inside ATLAS• Number of particles, energy and type
![Page 9: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/9.jpg)
C. Lebel 9 / 52
Approach for ATLAS: LayersApproach for ATLAS: Layers
All events are accepted
Particles depositing less than X keV are rejected
Minimum ionizing particles are rejected
Counting mode: all particles deposit more than X MeV in a single pixel
Low threshold
![Page 10: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/10.jpg)
C. Lebel 10 / 52
Approach for ATLAS: multiple areaApproach for ATLAS: multiple area
Polyethylene:Fast neutron
detection
6LiF:Thermal neutron
detection
Comet-type trackfrom protons
Cluster-type trackfrom α and triton
![Page 11: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/11.jpg)
C. Lebel 11 / 52
Adaptation of the Medipix2 device for Adaptation of the Medipix2 device for position sensitive detection of neutronsposition sensitive detection of neutrons
Silicon pixel detector can not detect neutrons directly. Conversion of neutrons to detectable radiation in a converter layer (via nuclear reactions or recoiled protons) deposited on the detector surface is needed.
Converter materials for thermal neutrons:6Li: 6Li + n a (2.05 MeV) + 3H (2.72 MeV)
10B: 10B + n a (1.47 MeV) + 7Li (0.84 MeV) + g (0.48MeV) (93.7%)10B + n a (1.78 MeV) + 7Li (1.01 MeV) (6.3%)
113Cd: 113Cd + n 114Cd + g (0.56MeV) + conversion electrons
155Gd: 155Gd + n 156Gd + g (0.09, 0.20, 0.30 MeV) + conversion electrons157Gd: 157Gd + n 158Gd + g (0.08, 0.18, 0.28 MeV) + conversion electrons
Converter for fast neutrons: polyethylene foil
Detector:150 – 700 mm thick silicon pixel detector
(pixel size 55 mm) bump bonded to
Medipix-2 readout chip.
![Page 12: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/12.jpg)
Equalization and Equalization and parametersparameters
![Page 13: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/13.jpg)
C. Lebel 13 / 52
EqualizationEqualization• Medipix is composed of 65536 pixel
channels. All are not created equal!– Pixelman allows for the equalization of the
low threshold (THL)• This is a small but necessary adjustment
• Two methods: – Use noise edge
• Useful to remove the noisiest pixels
– Use noise center• Centers the noise → This puts the necessary
offsets so that all pixels read the same energy
![Page 14: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/14.jpg)
C. Lebel 14 / 52
Parameters to adjustParameters to adjustTHL FBK
IKrum
![Page 15: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/15.jpg)
Particle detectionParticle detection
![Page 16: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/16.jpg)
C. Lebel 16 / 52
PhotonsPhotons• Photons can be detected in silicon only by
transferring their energy to charged particles.
Photoelectric effectAll energy transferred to the material Compton diffusion
Energy partially transferred to the material
Pair productionAll energy transferred to the material
![Page 17: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/17.jpg)
C. Lebel 17 / 52
PhotonsPhotons
http
://w
ww
.phy
sics
.nis
t.gov
/Phy
sRef
Dat
a/X
com
/Tex
t/XC
OM
.htm
l
![Page 18: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/18.jpg)
C. Lebel 18 / 52
Setup for sourcesSetup for sources
![Page 19: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/19.jpg)
C. Lebel 19 / 52
Photons – Photons – 5555FeFe• Production of X-rays with hν = 6 keV
– Primary interaction in silicon: Photoelectric effect• Energy of the photoelectrons:
E = hν – BE
for silicon, 1.8 keV is the binding energy of the K-shell (predominant at that photon energy)
Energy deposited by the photoelectron→ 4.2 keV
Range of such electrons < 1 μm (dE/dx = 7.33 keV/μm)
• Deposition is always in a single pixel!
![Page 20: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/20.jpg)
C. Lebel 20 / 52
Photons – 6 keV X-Rays (1 sec)Photons – 6 keV X-Rays (1 sec)
THL-FBK = 0.0000
THL-FBK = 0.0024
THL-FBK = 0.0049
![Page 21: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/21.jpg)
C. Lebel 21 / 52
Photons – 6 keV X-RaysPhotons – 6 keV X-Rays
![Page 22: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/22.jpg)
C. Lebel 22 / 52
Photons – Photons – 241241AmAm• Decays to 237Np, emitting alphas and gammas.
– Main gamma lines: 59.5 keV at 35.9 % and 26.3 keV at 2.4 %
• At 59.5 keV: – Photoelectric effect with the K-shell
• Energy of the electron: 57.7 keV• Range using CSDA approximation: ~30 μm
(Source:http://www.physics.nist.gov/PhysRefData/Star/ESTAR.html)
![Page 23: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/23.jpg)
C. Lebel 23 / 52
Photons – 60 keVPhotons – 60 keV
THL-FBK = 0.0000 THL-FBK = 0.0049 THL-FBK = 0.1074
![Page 24: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/24.jpg)
C. Lebel 24 / 52
Photons – 60 keV gammasPhotons – 60 keV gammas
THL-FBK = 0.0163 → E = 58 keV !
![Page 25: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/25.jpg)
AlphasAlphas
![Page 26: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/26.jpg)
C. Lebel 26 / 52
AlphasAlphas• Bethe-Bloch
Z
C
I
cm
A
ZNzcmr
dx
dE eAvogadroee 2
2ln
14
1 2222
2222
dE/dx
x
![Page 27: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/27.jpg)
C. Lebel 27 / 52
THL-FBK = 0.0000
THL-FBK = 0.3479
THL-FBK = 0.0116
THL-FBK = 0.6604
![Page 28: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/28.jpg)
C. Lebel 28 / 52
Changing Alpha EnergyChanging Alpha Energy
Eα = 4.20 MeV
Eα = 1.41 MeV
Eα = 0.69 MeV
The threshold is too The threshold is too low.low.
These energies cannotcannot calibrate the threshold
with this FBK.
The threshold is too The threshold is too low.low.
These energies cannotcannot calibrate the threshold
with this FBK.
![Page 29: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/29.jpg)
C. Lebel 29 / 52
Raising FBKRaising FBK
Eα = 4.20 MeV
Eα = 0.74 MeV
Tentatively:THL-FBK = 1.1719 → 735 keV
Tentatively:THL-FBK = 1.1719 → 735 keV
![Page 30: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/30.jpg)
C. Lebel 30 / 52
25
26
27
28
29
30
31
32
33
34
0 2 4 6 8 10
0
2
4
6
8
10
12
14
16
0 2 4 6 8 10
About full depletion voltage …About full depletion voltage …
biasU biasU
Flu
x (p
art/
sec)
Ave
rage
Clu
ster
Siz
e
4.478 MeV deposit → Range of ~21 μmCollection starts at 40 V → VVfd fd = 46 = 46 ± 1 V± 1 V
![Page 31: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/31.jpg)
C. Lebel 31 / 52
Cluster Size as function of UCluster Size as function of Ubiasbias
EE
![Page 32: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/32.jpg)
C. Lebel 32 / 52
Does the threshold depend on Does the threshold depend on the USB or the Medipix used?the USB or the Medipix used?
NO!
USB1-Medipix1
USB2-Medipix2
USB1-Medipix2(with USB2 equalization)
![Page 33: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/33.jpg)
ElectronsElectrons
![Page 34: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/34.jpg)
C. Lebel 34 / 52
THL-FBK = 0.0000THL-FBK = 0.0000 Electrons
Source 90Sr-YAverage electron
energy: 935 keV → mip
![Page 35: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/35.jpg)
C. Lebel 35 / 52
THL-FBK = 0.0275THL-FBK = 0.0275
THL-FBK=0.0000
Electrons
![Page 36: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/36.jpg)
C. Lebel 36 / 52
THL-FBK = 0.0519THL-FBK = 0.0519
THL-FBK=0.0275
Electrons
![Page 37: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/37.jpg)
C. Lebel 37 / 52
THL-FBK = 0.0842THL-FBK = 0.0842
THL-FBK=0.0519
Electrons
![Page 38: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/38.jpg)
C. Lebel 38 / 52
THL-FBK = 0.1324THL-FBK = 0.1324
THL-FBK=0.0842
Electrons
![Page 39: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/39.jpg)
C. Lebel 39 / 52
THL-FBK = 0.2875THL-FBK = 0.2875
THL-FBK=0.1324
Electrons
![Page 40: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/40.jpg)
C. Lebel 40 / 52
THL-FBK = 0.5194THL-FBK = 0.5194
THL-FBK=0.2875
Electrons
![Page 41: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/41.jpg)
C. Lebel 41 / 52
THL-FBK = 0.6000THL-FBK = 0.6000
THL-FBK=0.5194
Electrons
![Page 42: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/42.jpg)
C. Lebel 42 / 52
Some – very preliminary – results Some – very preliminary – results
Eα = 4.20 MeV
Eα = 0.69 MeV
Electrons
![Page 43: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/43.jpg)
C. Lebel 43 / 52
Some – very preliminary – resultsSome – very preliminary – results
6 keV X-Rays
60 keV Gammas
Electrons
![Page 44: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/44.jpg)
NeutronsNeutrons
![Page 45: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/45.jpg)
C. Lebel 45 / 52
Neutrons Neutrons detection through reaction with Polyethylenedetection through reaction with Polyethylene
• Using the reaction
n + 1H → p + n• Fast neutrons from
reactor
Thank you, Radek Skoda, for making this measurement possible!
![Page 46: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/46.jpg)
C. Lebel 46 / 52
Position of the polyethylene layerPosition of the polyethylene layer
Polyethylene Polyethylene
Polyethylene
![Page 47: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/47.jpg)
C. Lebel 47 / 52
Results obtained at the reactor SparrowResults obtained at the reactor Sparrow
![Page 48: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/48.jpg)
C. Lebel 48 / 52
Importance of thresholdImportance of threshold
THL-FBK = 0.1459FBK = 128
THL-FBK = 0.6268FBK = 200
THL-FBK = 0.8929FBK = 200
![Page 49: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/49.jpg)
C. Lebel 49 / 52
Examples of response of MEDIPIX-USB device Examples of response of MEDIPIX-USB device to fast monochromatic neutrons:to fast monochromatic neutrons:17MeV neutrons, flux about 1017MeV neutrons, flux about 1044 n/(s.cm n/(s.cm22))
• The direction of the neutrons with respect to the image was upstream (from bottom to top). The huge background is due to gamma rays which accompany neutrons. Half of the sensor (the right-hand side) was covered with a CH2 foil about 1.3 mm thickness.
• One can clearly recognize long and rather thick tracks of recoiled protons (up to 2 mm, vertically oriented) and big tracks and clusters generated via 28Si(n,α)25Mg, 28Si(n,p)28Al nuclear reactions in the body of the silicon detector. These events are displayed on the dense background caused by tracks and traces of electrons from interactions of gamma rays. One can even recognize that proton tracks shapes follows a Bragg law.
![Page 50: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/50.jpg)
C. Lebel 50 / 52
ConclusionsConclusions• ONEONE energy (58 keV) has been definitively
attributed to a threshold value• A threshold has been identified to isolate the
contribution of heavy charged particle from heavy charged particle from electronselectrons
• All USB and Medipix give the same variation as a function of effective threshold
• PhotonsPhotons, Heavy charged particlesHeavy charged particles and ElectronsElectrons give specific tracks which can be identified.
• Adding a Polyethylene layer allows the detection of fast neutrons
![Page 51: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/51.jpg)
C. Lebel 51 / 52
OutlookOutlook• More energy lines must be attributed to
specific values of THL-FBK– Different X-Rays!
• More on neutrons
• Analysis of heavy charged particle tracks: influence of plasma effect in silicon
![Page 52: Energy calibration of the threshold of Medipix for ATLAS](https://reader035.fdocuments.us/reader035/viewer/2022062519/56814edf550346895dbc7463/html5/thumbnails/52.jpg)
Děkuji vám!Děkuji vám!
Thank you!