# Presentation: 250902

## Slide 1

## Overview of Photo-Detector Properties
A Quick Look At:
MAPMT
MCPMT
SiPM
Photo-Cathode R&D
Conclusion

**A Quick Look At:**
**MAPMT**
**MCPMT**
**SiPM**
**Photo-Cathode R&D**
**Conclusion**

***Outline of Talk***

## Overview of Photo-Detector Properties

| Photodetector | Min. Time
Resolution | Feature
Size | Current
Min-Max | Gain | G | QE | Photo Converter |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Vacuum PMT | 300 pS | 1 cm | 5 nA-10 mA | 106 | 0 | 20% | Bialkali |
| MCPMT | 300 pS | 2 mm | 1 nA-100A | 106 | 3:1 | 20% | Bialkali |
| MCP | 10-30 pS | 1 mm | 10 nA-10A | 106 | 1:1.5 | 20% | Bialkali |
| PIN Diode | 1 nS | - | 1 A | 1 | 0 | 80% | Silicon |
| APD | 1 nS | 100 nm | 10 nA-100 nA | 102 | small | 80% | Silicon |
| SiPM (MRS) | 300 pS | 1 mm | ? | 106 | small | 40% | Silicon |

- Desirable Properties for Gamma-Ray Photo-Detectors

-  High Gain
-  High QE, 300-600 nm
-  No After Pulsing
-  Dynamic Range > 1000

-  Good Linearity
-  Low Dark Noise
-  Single pe Resolution
-  Fast Signal

- Adapted from
- J. Vanel, Cherenkov2005

**Inexpensive would be Nice...**

## Overview of Photo-Detector Properties

- Plot from Talk by
- J. Vanel, Cherenkov2005
- &  K. Arisaka

***Overview of Photo-Detector Properties***

## Overview of Photo-Detector Properties

***Overview of Photo-Detector Properties***

- Plot from Talk by
- J. Vanel, Cherenkov2005
- &  K. Arisaka

- Conventional PMTs

## Multi-Anode PMTs

***Multi-Anode PMTs***

**Principle of Operation**

- Photo & Drawing from Talk by
-      Tomasz Skwarnicki, BTeV

**Very Similar to Conventional PMT**

## Multi-Anode PMTs

- Photo from Talk by
-    Tomasz Skwarnicki, BTeV

## Multi-Anode PMTs

## Multi-Anode PMTs

**Tests of R8900 at Argonne – For Use in Trice **
**(ref. Byrum Talk this Workshop)**

- 4-Decade Filter Wheel

- XY Stage

## Multi-Anode PMTs

**Test Results of R8900 at Argonne **
**(Courtesy Bob Wagner, ANL)**

## Multi-Anode PMTs

***Multi-Anode PMTs***

**Another Candidate – 256 Channels**

## Multi-Anode PMTs

** ****High Gain**
** ****Good Pixel Size**
** ****Good pe Response**
** ****Good Linearity & Dynamic Range**
** ****Good Dark Count Rates**
** ****Fair Packaging,**
**   ****Some Improvement of Dead Space Needed**

***Multi-Anode PMTs***

** ****Not-So-Nice Features:**
** ****Pixel Non-Uniformity 2:1 – 3:1 Requires Calibration, LUTs**
** ****Triggering from Dynode Incurs**
**   ****Pixel Non-uniformity Penalty**
** ****Gains Limited to ~1E5 for NSB Rates,**
**   ****Reduces Resolution of Single pe Peak**
** ****Quantum Efficiency ~20%, Could Use Improvement**

## Micro-Channel Plates

- Drawings from Paper by
-    J. L. Wiza, NIM 162, 1976

## Micro-Channel Plates

## Micro-Channel Plates

- Testing to Begin At ANL
- Looking at Fast Timing

## Micro-Channel Plates

** ****Custom-Tailor Your Pixel Size**
** ****Good pe Response**
** ****Good Linearity & Dynamic Range**
** ****Good Pixel Uniformity, Might Still Need Calibration**
** ****Low Dark Count Rates**
** ****Excellent Timing Resolution**

** ****Not-So-Nice Features:**
** ****No Dynode for Trigger**
** ****Current-Return Path Not Well Defined Presently**
** ****Slow Recovery of Individual Channels, ~mSec**
** ****Quantum Efficiency ~20%, Could Use Improvement**
** ****Packaging Needs Improvement for Dead Space**
** ****Operates on 2000V**

***Micro-Channel Plates***

## Silicon Photo-Multipliers

**Principle of Operation**

- _Single Photodiode_

- Mode of Operation Depends on
-  Doping & Purity of Silicon
-  Bias Voltage
-  Geiger Mode Needs Quenching

- Adapted from Talk by
-    Nepomuk Otte, SNIC06

- APD

- SiPM

## Silicon Photo-Multipliers

**Principle of Operation**

- _Photodiode Array – Sum Individual Pixels_

- Photos from Talk by
-    V. Saveliev, 5/4/06

- Premise:  Pixels are So Small
-                 That 1 Pixel = 1 pe

## Silicon Photo-Multipliers

-  Sensitive Size 1x1 mm2 	24x24 = 576 pixels	32x32 = 1024 pixels
-       2x2 mm2, 4x4 mm2 Possible
-  Operating Voltage : 40 to 60V
-  Gain : 105 up to 106
-  Single Pixel Time Resolution :
-     ~ 100ps
-  Single Pixel Recovery Time :
-     ~1 s
-  No Sensitivity to Magnetic Fields

***Silicon Photo-Multipliers***

**Triggered Data, ~50 nS Gate**

- Adapted from Talk by
-    V. Saveliev, 5/4/06

## Silicon Photo-Multipliers

-  Dark Noise Rate:
-      ~1 MHz/mm2 @ Room Temp
-      ~1 KHz/mm2 @ 100°K
-  Optical Crosstalk
-        Hot-Carrier Luminescence
-        Improvements with Trenching
-  Dynamic Range
-       1 pe/pixel  Limit # Pixels

***Silicon Photo-Multipliers***

- Adapted from Talk by
-    J. Vanel, Cherenkov2005

**Triggered Data, 1 ********S Gate**
- (ANL Data, Bob Wagner)

- Adapted from Talk by
-    Nepomuk Otte, SNIC06

- ANL Teststand

## Silicon Photo-Multipliers

** ****Small Size**
** ****Low Operating Voltage**
** ****Good pe Resolution (If Do It Right...)**
** ****Good Linearity, Fair Dynamic Range**
** ****Good Timing Resolution**
** “****Potential” for Good QE (20% ******** 40% ******** 60%)**
** “****Potential” for Cheap Production (Not There Yet...)**
** ****Large Arrays, Direct Integration of Electronics Possible**

** ****Not-So-Nice Features:**
** ****Dark Current Rate is Significant**
****** ****Needs Cooling, or Coincidence Trigger, or High Thresh.**
** ****Optical Crosstalk Potentially a Problem**
** ****QE Needs Improvement**
** ****No Dynode for Trigger**

***Silicon Photo-Multipliers***

****** ****MAGIC is Considering**
**     ****SiPMs for New Telescope**

****** ****Not Quite in Production Yet...**

## Photo-Cathode R&D

- Higher QE=> higher cathode cost/area but smaller telescopes with lower mechanical costs ~D2.5, and smaller cathode area ~D2 (for a QE=50%, the mechanical cost would be reduced by a factor of >2.4 and reduced cathode area would compensate for higher cost/area)

***Photo-Cathode R&D***

- Slide Courtesy of
-            J. Buckley

## Photo-Cathode R&D

- MBE AlGaN/InGaN Cathode R&D
- Washington University Photocathode Group Buckley, Leopold and Rebillot

- Slide Courtesy of
-            J. Buckley

***Photo-Cathode R&D***

## Photo-Cathode R&D

- 0.8 eV (InN) and 6.2 eV (AlN) or 200 nm to > 1000 nm

***Photo-Cathode R&D***

- Slide Courtesy of
-            J. Buckley

## Photo-Cathode R&D

- Burle (Photonis) is currently integrating one of our AlGaN/InGaN cathodes into a conventional PMT - but still more device features to implement (thicker InN and higher In concentration for improved long wavelength response, improved lattice matching, intinsic gain), and many manufacturing details.

- Detected QE with HPMT in our chamber

***Photo-Cathode R&D***

- Slide Courtesy of
-            J. Buckley

## Conclusions

**  ****Active Photo-Detector R&D Programs in Many Technologies**
** ****Many Innovative Ideas being Pursued**
** ****Many Groups Active World-wide, in Development & Evaluation**
** ****Quite an Exciting Time for This Area**
***   ************ ******We Can Only Profit from this Development***
**  ****Still Too Early to Tell Which Technology Will be Best**
** ****Many Innovative Ideas being Pursued**
-    ********* ******With New Approaches, Need to Choose Technology Carefully***
** ****Personal Comments:**
**  ****MAPMTs are Friendly & Familiar; Need Better QE, & Uniformity**
**  ****MCPMTs Great for Fast Timing; Need Additional Study**
**  ****SiPMs Promising; Noise, Recovery, & Production Issues**
**  ****APDs – Good QE; Need Cooling, Need Low-Noise Elec.**
**  ****HPDs – Expensive, Good for B-Field, Better Options Exist...**

********* ******Elec. Dev.  Closely Coupled to Det.;  If ASICS, Need Time... ***