# Presentation: 125612

## CDF R5900 MAPMT Experiences

- Outline
- CDF usage
- Testing
- Performance
- Comments
- Not sure what to cover in this talk – threw in a bit of everything
- Been ~ 8 years since wrote req. – I have forgotten much

## Usage in Calorimeter - Overview

- Mechanical Structure
- Reuse existing Hadron steel
- Replace EM detector

- PES Detector Elements
- Scint. Strips + WLS readout

- (PES)

- PPR

## Shower Maximum Detector Elements

-  A position detector embedded at ~ 6  deep in the EM calorimeter measures the position
- of e’s and ’s
-  Sub-millimeter position resolution for energies > 100 Gev
-  6400 channels of 5mm strips
_**416 MAPMT’s**_

**Strips**

**Hamamatsu**
**R5900-M16**
**in CDF mount**

## Endplug Preshower

- First layer of EM section read out separately
- MAPMT’s are the same as used in the SMD(R5900-M16 Hamamatsu)
_**72 Tubes**_ used
- High Eta - use only 8 pixels/tube
- 1 cm thick tiles
- Same tower structure as EM(960 channels)

## Calorimeter Frontend Electronics

**(SMXR)**

- Schematic of Calorimeter and
- front end readout chain

**SMXR**

**ADMEM+**

**Schematic of Calorimeter and**
**  ****and Front end electronics readout**
**  ****path**

**On CAFE**

- SMD crate - 21 MAPMT’s
- Read out by each crate
- Green is RG-174 cabling
- From tubes

## Location – PMT boxes

- Common enclosure w/ Cal PMT’s
- Temp. controlled
- dark
- Laser - One pixel pulsed per MAPMT of PES and PPR
- Monitors tube gain - but only one pixel
- Assumption is that tube gain will drift for all pixels
- Impractical to do more than one pixel/tube in mixed system

## Numbers

- CDF bought 470(PES) + 80(PPR) tubes
- Use 416(PES) and 72(PPR) on detector
- 16*400 = 6400, so using 416 means we had some wasted channels
- PES cost - $1115/tube- bare
- Bases/mounts built by CDF
- Total cost for that + testing ~$200K
- Custom mount, CNC built to align well with 16 optical fibers delivering light

## Testing/performance

- Tubes generally received in good shape from Hamamatsu
- Rejected 12 tubes of 470, bulk had lost vacuum
- Bulk of tubes produced in 1996
- my memory is not so great
- Hamamatsu tubes may be different now...
- Tested
- Gain/QE
- Cross talk
- Linearity
- Stability
- Dark Current

## MAPMT Gains - Summary

- 3:1 specification max:min gain for pixels in a tube
- Average gains show no systematically “hot” or “cold” pixels

## Quantum Efficiency - Summary

- Preshower tubes show ~ 3% higher QE
- Produced 2 years after Shower Max
- Specification  is QE > 5%
- Good uniformity

## Cross Talk and Relative Gain

- _Relative Gain_
- Plots show pixel gain on MAPMT face
- 3 HV values(2 shown)
- Gain shown relative to highest gain pixel in tube
- Require <3:1 variation

- _Cross Talk_
- Signal seen in one pixel from light on another
- Each histogram “pixel” color shows % crosstalk for that pixel for light incident on one of the other 15
- Require < 5%

- Quite sensitive to fiber type delivering light, if there is any gap

## MAPMT Linearity

- 505 nm LED used
- Light intensity varied
- Stable, Linear Monitor Tube
- 400 counts= 100pC
- Require <10% dev at 100pC
**Tubes were quite marginal in this regard – many barely met the spec**

## Background Light Gain Stability

- Gain Stability for high and low “DC” background light
- Mimics high and low eta sections of det.
- Require < 5% gain shift in 24 hours
**Running experience is that they are quite stable in gain over the first two years – radioactive sources show minimal shift**

## Power Cycling Gain Stability

- Require <5% gain shift when cycling HV power

## Gain - Summary

- Correlation - Ham. Gain and UCLA
- Gain spread and Abs. Value within spec.

## MAPMT Dark Current

- Dark current provides floor for radioactive source current measurements
- < 100 pA dark current makes negligible contribution to measurement error

## Comments

- Good 1⁄4” tubes – not the same as larger ones
- Linearity in our tubes was not great
- Lots of connections at rear of tube
- CDF chose to make the connector at the tube
- Cheap connectors  numerous single channel problems after several recablings
- Soldered cables to transition boards
- Might have been better (more costly also) to solder at the tube end and put a connector at the electronics
- Need to control the fiber/tube face gap carefully
- Reflections can cause cross talk
- Integration is important
- Minos probably has much more current data