Analysis of DHCAL Data
José Repond
Argonne National Laboratory
CALICE Collaboration Meeting
Shinshu University, Matsumoto, Japan
March 5 – 7, 2012
DHCAL Analysis Efforts
Noise studies – Guang Yang (Illinois Institute of Technology)
Lei Xia (Argonne National Laboratory)
Muon measurements – For updates look at DHCAL simulation talk
Secondary beam studies – Burak Bilki (Argonne and University of Iowa)
Software compensation – Jacob Smith (Argonne and UTA), will report next time
Fractal analysis – Check out Manqi Ruan’s talk
2
Noise studies
In general
Noise rate quite small and does not affect measurements
Depends on T and p
Does it depend on activity in the DHCAL?
Shape measurements
Very sensitive to outliers (each hit has same weight!)
Requires careful study
Noise rate measurements
Trigger-less runs taken regularly (at least twice a day)
Trigger-less runs taken during beam spills as well
Random trigger runs taken over night
Noise events
Reconstructed with event builder
Hits sorted in time
Hits grouped into one event until gap of > 500 ns
3
Classification of noise events
1.
2.
3.
4.
5.
6.
7.
Low multiplicity random noise
High multiplicity random noise
Cosmic ray or beam muon event
Ground connector noise
Board noise
Ground connector + board noise
Non-muon beam event
These categories are
now orthogonal
Ground connector noise
In future will mask 4 pads from each board
Won’t have to deal with this anymore
4
Correlation with GND connector noise
Sum of time spans
between end of
previous events and
end of this event
Noise
classification
1
2
3
5
7
Low
multiplicity
random
noise
High
multiplicity
random
noise
Cosmic ray
or beam
muon
Board noise
Non-muon
beam event
Time span T
482554709
7172995
432102
309399
539
Number N
of GND
connector
hits
9642
16545
493
21184
150
Rate = N/T
0.000020
0.0023
0.00114
0.06847
0.27829
Note: rate of GND connector noise appears to be correlated to activity in detector
5
Secondary Beam Studies
6
Topological Particle Identification
Cleaning cuts
Exactly 1 cluster in layer 0
Not more than 3 hits in layer 0
At least 4 layers with hits
TPI being developed as
an alternative to using
the sometimes inefficient
Čerenkov
Identify last layer i of MIP stub
Layer i+2 → hits within 3-7 cm of MIP stub
Layer i+1 → hits within 3-7 cm of MIP stub
Layer i
→ no hits within 3-7 cm of MIP stub
LlastMIP = 1
Identify last layer with hits
Llast
Identify muons
if(LlastMIP = Llast) → μ
Reduce leakage
LlastMIP < 11 for p <32 GeV/c
LLastMIP < 7 for p 32 GeV/c
7
In the interaction region (L>LLastMIP)
Identify track segments with clusters with ΔR<3 cm
Identify pions
If at least 2 track segments with hits in at least 4 layers →π
Define 3D compactness index CI
CI =
2
r
i
20 GeV
N
with ri2 = (xi – x0)2 + (yi – y0)2 + (zi – z0)2,
(x0, y0, z0) = barycenter of shower and
∑ is over hits in L>LLastMIP
Define asymmetry index A
A=
N1  N 2
N1  N 2
with N1 (N2)= hits in first (second) half of shower
e+
π+
8
Calibration
Use
Muon data
Track segments in secondary beam data
RMS = 17%
Explored several ways
Establish calibration factor for each pad individually
→ lack of statistics introduces additional smearing
Factorize
C = CRPC(i,z) x Cplane(x,y)
with CRPC = constants for each RPC
Cplane = average calibration as function of x,y
Several explanations for hot spots
9
Results: Linearity
Uncalibrated
Calibrated
Note
Linearity mostly improved (apart from 4,6 GeV/c points)
10% drop at E>28 GeV predicted by simulation
10
Results: Resolution
Uncalibrated
Calibrated
Note
Calibration makes resolution if anything a bit worse
Prediction was for 58%/√E  0%
11
Conclusions
Noise study
Guang just started
Classification of noise complete
Studies of rates/correlations beginning
Secondary beam studies
Topological particle identification almost ready
Calibration is tough!
Comparison with simulation coming soon
12