timepix digitization
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see below. I simulate a line profile(21000 10 keV gammas) I use the timepix digitization I use count mode. The blue dots are the energy depositions. I some times observe that neighbour pixels have a large number of counts (red pixels). Does anybody have an idea if this is a real thing or is this a bug?
Erik, that long track is not a 10keV electron, is it ? I am guessing you
are sending a high energy MIP. The red dots
are not a bug. They are very real, they are delta rays :) !
J.
On Thu, Apr 21, 2016 at 12:10 PM, emx77 notifications@github.com wrote:
see below. I simulate a line profile(21000 10 keV electrons) I use the
timepix digitization I use count mode. The blue dots are the energy
depositions. I some times observe that neighbour pixels have a large number
of counts (red pixels). Does anybody have an idea if this is a real thing
or is this a bug?[image: allpix-example]
https://cloud.githubusercontent.com/assets/17120833/14705395/8db5802a-07b9-11e6-8a68-a9f64ec39d65.png—
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#22
these are 10 keV gammas entering perpendicular to the sensor. What I think is strange is that there are no energy depositions in the red pixels.
ok, no ... something is very strange here ... how can a 10keV photon make
such a track ? We can look at it together.
J.
On Thu, Apr 21, 2016 at 12:15 PM, emx77 notifications@github.com wrote:
this are 10 keV gammas entering perpendicular to the sensor. What I think
is tstrange me is that there are no energy depositions in the red pixels.—
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#22 (comment)
it is not a single track. The image contains multiple short tracks (21000).
Cheers, Erik.
to reproduce I have added my applied macros and model.
# Detector
/allpix/det/setId 500
/allpix/det/setPosition 0.0 0.0 0.0 mm
/allpix/det/setRotation 0.0 0.0 0.0 deg
/allpix/det/setLowTHL 13. keV
# Appliances
# Extra volumes placed with respect to the center of the wrapper.
# The wrapper is the envolvent volume of the medipix. This volumes
# rotate with the Medipix !
# The command:
# /allpix/extras/setWrapperEnhancement --> extends the wrapper !
# [HINT!] If you want your appliance touching the Si wafer, the
# center of the volume should be z_coordinate =
# half_appliance + (PCB + Si - Enhance)/2.
# z coordinate = 0 --> (on top of the PCB)
# z coordinate = -1* (PCB + appliance) --> behind the PCB
#/control/alias appPosZ -3.750
#/control/alias enhanceZ 5.0
#/allpix/extras/setTestStructurePosition 0. 0. 50. mm
#/allpix/extras/setTestStructureType 200
#/allpix/extras/setAppliancePosition 0 0 0 mm
#/allpix/extras/setWrapperEnhancement 0. 0. {enhanceZ} mm
/allpix/extras/setWorldMaterial Vacuum
################################################
# Max step lenght. Applies only to the sensor
/allpix/det/setMaxStepLengthSensor 10 um
################################################
# initialize
/run/initialize
################################################
# Build detectors
/allpix/det/update
####################################################################
# prefix for output filename (string) Don't use quotation marks \"
/allpix/config/setOutputPrefixWithPath test
# GPS
/control/execute macros/em_source.in
/run/verbose 0
/control/verbose 0
/control/saveHistory
/tracking/verbose 0
/allpix/phys/verbose 0
/event/verbose 0
# Run
/run/beamOn 21000
em_source.in:
#########################
# GPS
/gps/particle gamma
#/gps/pos/type Plane
/gps/energy 10 keV
#/gps/position 0.0275 0.0275 4 mm
#/gps/pos/rot1 0 0 1
#/gps/pos/rot2 1 0 0
/gps/pos/type Plane
/gps/pos/shape Rectangle
/gps/pos/centre 0.0 0.0 2.0 mm
/gps/pos/halfy 7040. um
/gps/pos/halfx 0. um
/gps/pos/rot1 0.999848 0.017452 0
/gps/direction 0 0 -1
#/gps/ene/type User
#/gps/hist/type energy
# spectra
#/control/execute macros/gps_source_ASI_50kVp_XRayTube.mac
#/gps/hist/point 0.1 1
# /gps/number 1
#/gps/source/list
detector model:
<!-- Timepix -->
<pixeldet id="500,501,502,503,504,505,506,507,508,509,510">
<digitizer>Timepix</digitizer>
<npix_x>256</npix_x>
<npix_y>256</npix_y>
<npix_z>0</npix_z>
<pixsize_x units="um">27.5</pixsize_x>
<pixsize_y units="um">27.5</pixsize_y>
<pixsize_z units="um">150</pixsize_z>
<chip_hx units="um">7055.5</chip_hx>
<chip_hy units="um">8060</chip_hy>
<!-- 350 -->
<chip_hz units="um">350</chip_hz>
<chip_offsetx units="um">0.</chip_offsetx>
<chip_offsety units="um">-1020.</chip_offsety>
<chip_offsetz units="um">0.</chip_offsetz>
<sensor_hx units="um">7040.</sensor_hx>
<sensor_hy units="um">7040.</sensor_hy>
<sensor_hz units="um">150</sensor_hz>
<!--
<coverlayer_hz units="um">0.5</coverlayer_hz>
x<coverlayer_mat>G4_Al</coverlayer_mat>
-->
<sensor_gr_excess_htop units="um">500.0</sensor_gr_excess_htop>
<sensor_gr_excess_hbottom units="um">500.0</sensor_gr_excess_hbottom>
<sensor_gr_excess_hright units="um">500.0</sensor_gr_excess_hright>
<sensor_gr_excess_hleft units="um">500.0</sensor_gr_excess_hleft>
<sensor_posx units="mm">0</sensor_posx>
<sensor_posy units="mm">22.25</sensor_posy>
<sensor_posz units="mm">0.</sensor_posz>
<bump_radius units="um">9.0</bump_radius>
<!-- 20.0 -->
<bump_height units="um">20.0</bump_height>
<bump_offset_x units="um">0.0</bump_offset_x>
<bump_offset_y units="um">0.0</bump_offset_y>
<bump_dr units="um">2.0</bump_dr>
<pcb_hx units="mm">23.50</pcb_hx>
<pcb_hy units="mm">39.5</pcb_hy>
<!--0.88-->
<pcb_hz units="mm">0.88</pcb_hz>
<sensor_resistivity>4000.0</sensor_resistivity>
<MIP_Tot> 160 </MIP_Tot>
<MIP_Charge> 24000.</MIP_Charge>
<Counter_Depth> 65536 </Counter_Depth>
<Clock_Unit> 25e-9 </Clock_Unit>
<Chip_Noise>300.</Chip_Noise>
<Chip_Threshold>800</Chip_Threshold>
<Cross_Talk>0.001</Cross_Talk>
<Saturation_Energy>350.</Saturation_Energy>
</pixeldet>
Ok I think I found it: What I see are noisy pixels that together with some charge from a neighbour pixel are above threshold.