First Look at FLASH Thick Target Test Beam (Jan 2004) Results The Alumina Underground Jan. 13, 2004.
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Transcript of First Look at FLASH Thick Target Test Beam (Jan 2004) Results The Alumina Underground Jan. 13, 2004.
![Page 1: First Look at FLASH Thick Target Test Beam (Jan 2004) Results The Alumina Underground Jan. 13, 2004.](https://reader030.fdocuments.net/reader030/viewer/2022033105/5697bfc31a28abf838ca53d6/html5/thumbnails/1.jpg)
First Look at FLASH Thick Target Test Beam (Jan 2004)
Results
The Alumina Underground
Jan. 13, 2004
![Page 2: First Look at FLASH Thick Target Test Beam (Jan 2004) Results The Alumina Underground Jan. 13, 2004.](https://reader030.fdocuments.net/reader030/viewer/2022033105/5697bfc31a28abf838ca53d6/html5/thumbnails/2.jpg)
Target Setup
• Alumnia bricks are 6”x4”x2”
• Assume 3” of alumina ~ 1 r.l.
• Picture shows ~14 r.l. of target
![Page 3: First Look at FLASH Thick Target Test Beam (Jan 2004) Results The Alumina Underground Jan. 13, 2004.](https://reader030.fdocuments.net/reader030/viewer/2022033105/5697bfc31a28abf838ca53d6/html5/thumbnails/3.jpg)
Target Setup
• Target thickness reduced by removing bricks from the updtream end of pile
• Picture shows ~10 r.l. target
![Page 4: First Look at FLASH Thick Target Test Beam (Jan 2004) Results The Alumina Underground Jan. 13, 2004.](https://reader030.fdocuments.net/reader030/viewer/2022033105/5697bfc31a28abf838ca53d6/html5/thumbnails/4.jpg)
Background Measurement
• Background measured using 6 “blind” PMT• These are located behind at least 30 r.l. of
lead shielding from target• 2” and 4” optical channels alternately tried• Signals seen in time with beam, but many
late hits.• ADC results analyzed using standard
calibration of PMT from Stan Thomas
![Page 5: First Look at FLASH Thick Target Test Beam (Jan 2004) Results The Alumina Underground Jan. 13, 2004.](https://reader030.fdocuments.net/reader030/viewer/2022033105/5697bfc31a28abf838ca53d6/html5/thumbnails/5.jpg)
Background at 2000V, 2” optical channel
![Page 6: First Look at FLASH Thick Target Test Beam (Jan 2004) Results The Alumina Underground Jan. 13, 2004.](https://reader030.fdocuments.net/reader030/viewer/2022033105/5697bfc31a28abf838ca53d6/html5/thumbnails/6.jpg)
Background at 2000V, 2” optical channel
![Page 7: First Look at FLASH Thick Target Test Beam (Jan 2004) Results The Alumina Underground Jan. 13, 2004.](https://reader030.fdocuments.net/reader030/viewer/2022033105/5697bfc31a28abf838ca53d6/html5/thumbnails/7.jpg)
Background at 2000V, 4” optical channel
![Page 8: First Look at FLASH Thick Target Test Beam (Jan 2004) Results The Alumina Underground Jan. 13, 2004.](https://reader030.fdocuments.net/reader030/viewer/2022033105/5697bfc31a28abf838ca53d6/html5/thumbnails/8.jpg)
Background at 2000V, 4” optical channel
![Page 9: First Look at FLASH Thick Target Test Beam (Jan 2004) Results The Alumina Underground Jan. 13, 2004.](https://reader030.fdocuments.net/reader030/viewer/2022033105/5697bfc31a28abf838ca53d6/html5/thumbnails/9.jpg)
Target variation
• Worst case of background appears to be at 10 r.l. and only marginally (~10-15%) different from 14 r.l.
• Average background level equivalent to ~30-40 p.e. at 107 e- per pulse and 10 r.l.
• Decrease by ~30-40% from 10 r.l. to 6 r.l.
• Minimal background at 2 r.l.
![Page 10: First Look at FLASH Thick Target Test Beam (Jan 2004) Results The Alumina Underground Jan. 13, 2004.](https://reader030.fdocuments.net/reader030/viewer/2022033105/5697bfc31a28abf838ca53d6/html5/thumbnails/10.jpg)
Target variation (cont’d)
• The variation of the background vs. target thickness is inconsistent with GEANT prediction for gamma background
• + large number of late hits suggests we are probably dominated by neutrons
• PMT4 calibration is probably off; the other 5 are quite consistent
![Page 11: First Look at FLASH Thick Target Test Beam (Jan 2004) Results The Alumina Underground Jan. 13, 2004.](https://reader030.fdocuments.net/reader030/viewer/2022033105/5697bfc31a28abf838ca53d6/html5/thumbnails/11.jpg)
2” and 4” optical channel comaprison
![Page 12: First Look at FLASH Thick Target Test Beam (Jan 2004) Results The Alumina Underground Jan. 13, 2004.](https://reader030.fdocuments.net/reader030/viewer/2022033105/5697bfc31a28abf838ca53d6/html5/thumbnails/12.jpg)
2” vs. 4”
• Difference in background between 2” and 4” optical channel configuration is small (less than ~10-20%)
![Page 13: First Look at FLASH Thick Target Test Beam (Jan 2004) Results The Alumina Underground Jan. 13, 2004.](https://reader030.fdocuments.net/reader030/viewer/2022033105/5697bfc31a28abf838ca53d6/html5/thumbnails/13.jpg)
Varying HV: 2000V vs. 1600V
![Page 14: First Look at FLASH Thick Target Test Beam (Jan 2004) Results The Alumina Underground Jan. 13, 2004.](https://reader030.fdocuments.net/reader030/viewer/2022033105/5697bfc31a28abf838ca53d6/html5/thumbnails/14.jpg)
Varying HV: 2000V vs. 1200V
![Page 15: First Look at FLASH Thick Target Test Beam (Jan 2004) Results The Alumina Underground Jan. 13, 2004.](https://reader030.fdocuments.net/reader030/viewer/2022033105/5697bfc31a28abf838ca53d6/html5/thumbnails/15.jpg)
HV variation
• No Discernible HV variation in background level estimate…suggests that background is dominated by electrons from photo-cathode
![Page 16: First Look at FLASH Thick Target Test Beam (Jan 2004) Results The Alumina Underground Jan. 13, 2004.](https://reader030.fdocuments.net/reader030/viewer/2022033105/5697bfc31a28abf838ca53d6/html5/thumbnails/16.jpg)
Conclusion
• Background probably dominated by neutrons
• Maximum background level is equivalent to ~30-40 p.e. at 107 electrons per pulse.
• 2” and 4” optical channels give similar background levels
• Equivalent background level does not change with HV between 1200-2000 V.