1. RIKEN VTX Software Meeting
Large Cluster Rate
Takashi HACHIYA
RIKEN
2011/10/20
RIKEN VTX Software Meeting

2. RIKEN VTX Software Meeting
Pixel Event Display
Red Box : hit pixel
Black circle : cluster
Box region is expanded
Event display for pixel sensors
Top plots shows a normal hit pattern.
Problem1:
Bottom plots shows large clusters
Left: rawhit spread in the single column. I guess the electronics problem happen in this event. This should be removed.
Xsize:large
Zsize:small
Right: hadronic interaction in a sensor. Can not remove this.
Zsize:large
Sensor Height
Sensor Width
Sensor Height
Sensor Height
2011/10/20
RIKEN VTX Software Meeting
Sensor Width
Sensor Width

3. RIKEN VTX Software Meeting
Pixel Cluster 2
X-width of large cluster is spread to sensor-wide.
dx(cm) dx
dx = X(rawhit)-X(cluster)
dz = Z(rawhit)-Z(cluster)
X-Width of sensor
dx(cm)
dz(cm)
Problem2:
Algorithm
Rawhit where places next to x-axis or z-axis is connected.
But next to X and Z axis should be also connected. OK
Not connected
2011/10/20
RIKEN VTX Software Meeting

4. Study on Large Cluster Rate
Studied how much the large cluster is generated compared to the normal cluster.
Definition
Large Cluster :
Xsize>20 && Zsize<5
Straight line shape
Appearance rate of the large cluster
Rate = N_Lcluster/N_cluster
This value is calculated event by event and chip by chip
No Hot&Dead map is applied
Hot&Dead map has something problem. Now on investigating by Sako-san
Run349679
1100 event used.
|zbbc|<5cm
Ncluster/chip
NLargeCls/chip
Large Cluster Rate
2011/10/20
RIKEN VTX Software Meeting

5. RIKEN VTX Software Meeting
LargeCluster Rate
Large Cluster Rate vs ChipID B0 B1
Rate histo (0,0)
Rate histogram for channels
Average hit rate shows almost zero for most of the channels
Some has problem
Average Lcluster Rate histograms shows almost zero.
Same histogram with different X-axis range.
Less than 0.01% in average
Sometime large rate exist. It might be due to hot channel
2011/10/20
RIKEN VTX Software Meeting

6. Chip by Chip Rate for appearance
West
East B0
0-1 B1
2011/10/20
RIKEN VTX Software Meeting
Rate is almost 0 (less than 0.1%) for most channels. But some channel is large. Should be Hot channel

7. RIKEN VTX Software Meeting
Occupancy
Chip by Chip occupancy is calculated using cluster.
HitSize = size
It looks:
HitSize using All clusters increases with larger bbcq
HitSize using Lsize clusters is independent of bbcq. B0 B1
Higher HitSize is caused by Lsize Cluster.
All cluster
All cluster
HitSize
HitSize
bbcq
bbcq
Lsize Cluster
Lsize Cluster
HitSize
HitSize
2011/10/20
RIKEN VTX Software Meeting
bbcq
bbcq

8. RIKEN VTX Software Meeting
Occupancy2
The peak at 3% is made from Lsize cluster.
Hot&Dead map is not applied.
Based on cluster size, occupancy (per chip) is 2% and 1% for B0 and B1 as maximum after the Lsize cluster is removed.
Occupancy depends on the status of the ladder.
Threshold
HitSize at B0
All clusters
Lsize clusters
HitSize at B1
All clusters
Lsize clusters
2011/10/20
RIKEN VTX Software Meeting

9. RIKEN VTX Software Meeting
Summary
Lsize cluster rate: less than 0.01% in average
Need to study without hot channel
Occupancy
2% and 1% as maximum for B0 and B1
Lsize clusters cause large occupancy
Maximum value depends on chip condition
Different for chip by chip
Problem?
Size is not match with Nrawhit
There might be some mis-reconstructed clusters.
2011/10/20
RIKEN VTX Software Meeting

10. RIKEN VTX Software Meeting
Appearance rate vs ChipID (same as p3)
2011/10/20
RIKEN VTX Software Meeting

11. Automatic production of hot/dead pixel maps
Sako-san’s slide (2011/6/13)
Automatic production of hot/dead pixel maps
Analyze DSTs of each run and creates hit pixel map histograms
Creates also hot and dead pixel maps for based on rate threshold / pixel (this is also saved in the file)
Definition of Hot pixels:
#hit/event > 0.01 at Layer0
#hit/event >0.003 at Layer1
Definition of Dead pixels:
#hit/event =0
hot
hot
hot
hot
2011/10/20
RIKEN VTX Software Meeting