1. Medipix2 meeting Dec. 2005 Medipix Activity at Berkeley John Vallerga, Jason McPhate, Anton Tremsin and Bettina Mikulec

2. Medipix2 meeting Dec. 2005 Contents l Tube Fabrication Progress –Header –Body –Medipix bake to 350 C l Neutron Detector Concept Medium Infra-red ( = 5  m) APD array

3. Medipix2 meeting Dec. 2005 Image Tube progress Header assembly (interior)

4. Medipix2 meeting Dec. 2005 Image Tube progress Glued and wire bonded

5. Medipix2 meeting Dec. 2005 Image tube progress Header assembly (exterior)

6. Medipix2 meeting Dec. 2005 Image tube progress Tube body stackup before brazing

7. Medipix2 meeting Dec. 2005 High Temperature Bake l Vacuum bake Medipix2 mounted on ceramic header l Temperature profile to match tube processing l Class C Medipix2 chip (D9) l Initial bake to 300C for 10 hour (turbo failed) l Used DAC scans and threshold equilisation to characterize chip before and after bake. l No apparent change l Second bake 24 hours, with 10 hours at 350C. l Again no apparent change

8. Medipix2 meeting Dec. 2005 Neutron sensitive MCPs l Glass microchannel plates with 10 B as a major dopant l Manufactured by Nova Scientific (Sturbridge Mass., USA) l High thermal neutron cross section High spatial resolution as range of daughter products ~ 3 to 4  m in glass l Can also be made with Gd 2 0 3 dopant and used as a passive collimator l Medipix2 readout useful for high flux, fast tomography

9. Medipix2 meeting Dec. 2005 10 B neutron capture reaction 10 B(n,  ) 7 Li reaction  =3837 barns for thermal neutrons and 8500 for cold neutrons

10. Medipix2 meeting Dec. 2005 Neutron capture reaction n 7 Li 4 He n Secondary electrons 10 B Secondary electrons 10 B(n,  ) 7 Li reaction,  =3837 barns

11. Medipix2 meeting Dec. 2005 Angular selective neutron detection Secondary electrons No bias applied to front MCP Angular selective Bias applied to front MCP All neutrons are detected

12. Medipix2 meeting Dec. 2005 Infra-red sensitive Medipix! l APD arrays seem a natural match to Medipix style readout l High optical QE, no vacuum tube! l Difficult mechanical/fabrication issues –Backside illumination –Optical and electrical crosstalk between pixels –High excess noise factors l DRS technologies has a new Hg x Cd 1-x Te process that can solve many of these issues concurrently and might be a good match to Medipix –Medium infra-red sensitive –Gain of 1000 ± 31

13. Medipix2 meeting Dec. 2005 MWIR APD Arrays DRS Technologies

14. Medipix2 meeting Dec. 2005 APD Gain vs Bias = 4.3  m, 77K = 2.2  m, 273K

15. Medipix2 meeting Dec. 2005 Excess Noise Factor

16. Medipix2 meeting Dec. 2005 Status of idea l Preliminary discussions with DRS found no obvious problems l Sensor has high dark current so must be operated at 77º K l Questions –Can Medipix2 operate at this low temperature –Is Medipix2 a strong source of IR radiation l Applications –Best IR sensors have ~6 e- readout noise at slow rates –Adaptive optics tip/tilt sensors, wavefront sensors in science bandpass –High frame rate IR imaging