Elena Rocco Nikhef Utrecht University 24 th October 2013 C urrent status Detector in use FoCal prototype 24 layers 96 chips MIMOSA 23 Non uniform response f rom the testbeam ID: 342895
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Slide1
MIMOSA 23 settings
Elena Rocco
Nikhef
-Utrecht University
24
th
October 2013Slide2
Current
status
Detector in use:
FoCal prototype; 24 layers , 96 chips (MIMOSA 23)Non uniform response: from the testbeam data analysis we noticed that we have large variation in sensitivity from chip to chipSettings in use: settings used during the test beam: Vref2=80 Vref1 optimised per single chipTests in lab:“pedestal” measurements -> systematic studies in Vref1 and Vref2Cosmic data taking (for given threshold settings to study the MIP response) Only digital R/0 available (no voltage reading)
10/24/13
E. Rocco
2Slide3
Open points (1)
I
mpossibility
to get the discriminator transfer function normalised from 0 to 110/24/13E. Rocco3Slide4
Open point (2)
The normalisation of the firing pixels to 1 hides possible pathological behaviour
10/24/13
E. Rocco4Slide5
Open point (3)
Different Vref1 settings -> different discriminator transfer
functions
10/24/13E. Rocco5Slide6
Open point (3) another example
10/24/13
E. Rocco
6Slide7
Open point (4): unbalance left-right
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E. Rocco
7All the chips have Vref2=80: unexpected unbalance!!!Some unbalanced chips present hot columns/rows/pixels Slide8
Open point (4)
Scan in Vref2 looking at the unbalance
left-right
10/24/13E. Rocco8Slide9
Open point (4) another example
Scan in Vref2 looking at the unbalance
left-right
10/24/13E. Rocco9Which is the procedure to get the best Vref2 value then?Slide10
Open point (5)
The discriminator transfer function fit
10/24/13
E. Rocco10From the paper (NIM A 602 (2009) 461-466). “..One can fit with an erf (error function) to this curve. Its derivative gives a gaussian (normal) distribution.the FWHM is ~2.35 σ
, and its mean give the offset of the comparator, where σ is the rms
temporal noise.”
Question: can we do
th
e same operation but with the digital readout?Slide11
Open point (6):
clustersize
(chip 8&9)
10/24/13E. Rocco11Slide12
Open point (6):
clustersize
(chip
10&11)10/24/13E. Rocco12Slide13
More questions might come….
THANK YOU!
10/24/13
E. Rocco13