# Presentation: 509589

##        SMT Status 	                     and Performance

- Markus Warsinsky
- Bonn University

** ****Introduction**
** ****Water Leak**
** ****HV issues**
** ****SMT Results and Performance**
** ****Summary**

***       ******SMT Status ******	******                     and Performance***

## SMT Overview

- 6 Barrels

- 12 F-Disks

- 4 H-Disks

** ****Barrel Detectors measure central tracks**
** ****Disk Detectors for forward tracking**
** ****6   Barrel (each 12cm long)****	****|z| < 38.4 cm****	****2.7 cm < R < 9.5 cm**
** ****12 F-Disks****	****	****	****	****	****|z| < 54.8 cm****	****2.6 cm < R < 10.5 cm****	**
** ****4   H-Disks****	****	****	****	****	****|z| < 120 cm****	****9.5 cm < R < 26 cm**
** ****793.000 readout channels**

**Percentage of working devices:**
**Barrel:****	****~95%, F-disks:  ~95%, H-disks:****	**** ~87%**

-  additional noise problems on F-wedges under investigation

## The Water Leak problem

-  access to cathedral area on   thursdays (04/11) access
-  water leak was found in heat  exchanger for one interface  board crate

**Interface Boards**
- 8 Crates (144 Boards in total)
- Refresh signals and adjust timing
- SVX monitoring and  power supply
- Biasvoltage-distribution

** ****interface board crates BEFORE**
** ****cabling**

##  repair of heat-exchanger possible   only by taking crate out   (~2-3 days of work in cathedral)

-  repair of heat-exchanger possible   only by taking crate out   (~2-3 days of work in cathedral)
-  decided to disconnect water and run  it air-cooled only
-  dissipate 450W
-  hottest spots were around 38 oC
-  crate runs ~10 oC hotter  than others
-  stable after  closing detector

- temperature (oC)

- time (min)

## High Voltage Rampdown

-  can't sink charge
-  filtering capacitors on bias lines (~few F)
-  have to discharge over 100M resistor  in HV pods  slow rampdown

-  BiRa 4877 HV   modules located  in counting house
-  Cockcroft-Walton  generators

- U(V)

- time(min)

- 10 min

-  long rampdown time for high voltage  lose beamtime

## Solution: Bleeding Resistors

-  add additional resistor in parallel to sensors
-  ~2-10 M
-  reduces discharge time
-  currently down to 4 minutes, expect 3 minutes by end of the week
-  additional current ~10A
-  working on modified monitoring to subtract extra current

## SMT Calibration

- Pedestal mean

- Pedestal width (Noise)

- channel nr.

- channel nr.

- B1-6-12

- ADC counts

- ADC counts

-  take calibration data  during quiet time
-  used for:
- setting chip-wide thresholdsfor online sparsification
- offline pedestal subtraction
-  calibration runs ~ once per week

## SMT Clusters

- p-side pulse-height (ADC)

- n-side pulse-height (ADC)

- 1 mip = 4 fC = 25 ADC counts

- S/N  > 10
- as expected!

**ADC counts**

- pulse-height correlation
- between p- and n-side

-  hit efficiency studies underway, look promising

## Alignment and DCA resolution

**Alignment and DCA resolution**

- pt > 1 GeV
- ~ 76 m

- pt > 3 GeV
- ~ 62 m

-  a lot of efforts on  SMT alignment
-  necessary for good  DCA resolution
-  DCA-distributions for  SMT stand-alone  tracks with newest  alignment:

- SMT track DCA (cm)

- SMT track DCA (cm)

##                         SMT results

**                        ****SMT results**

- reconstructed with SMT only tracks
- explicit V0 reconstruction

## Radiation issues

**Radiation issues**

-  integrated dose so far:
- 				~10 krad
-  SMT is radiation hard to 2 Mrad
-  step 13 losses down to
-   ~4-5 rad per shot-setup
-  March 30th: 		~0.08 rad in ~5 min
-  SMT is running unbiased but with  low voltage on during shot-setup  and beam studies

## Summary

**Commissioning/Operation**
- approx. 93% of all channels can be read out
- used thursday's access to fix water leak by disconnectingdefective heat exchanger
- affected crate can be powered and used air-cooled only
- working on reduction of HV rampdown time
**Results**
- Calibration, Resolution and Alignment studies look promising
- Studies regarding noise, clustering, efficiency and track-reconstruction are ongoing