| Peter Križan | |
| University of Ljubljana and J. Stefan Institute | |
| For Belle Aerogel RICH R&D group | |
Proximity focusing RICH in the forward region
| K/p separation at 4 GeV/c | |
| qc(p) ~ 308 mrad ( n = 1.05 ) | |
| qc(p)– qc(K) ~ 23 mrad | |
| dqc(meas.) = s0 ~ 13 mrad | |
| With 20mm thick aerogel and 6mm PMT pad size | |
| ŕ 6s separation with Npe~10 |
Beam test: Cherenkov angle resolution and number of photons
How to increase the number of photons?
FOCUSING CONFIGURATION
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low momentum
FOCUSING CONFIGURATION
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momentum scan
FOCUSING CONFIGURATION - inclined tracks
Defocusing configuration, data
| Reported last year: better optical quality for n~1.05 hydrophobic aerogel | |
| a new solvent (Di-Methyl-Formamide instead of Methyl-alcohol) | |
| precursor (Methyl-silicate-51) from a different supplier | |
| -> considerable improvement | |
Aerogel production: multilayer samples
| Cut into hexagonal shape from a square block | ||
| Machining device: use “water-jet” thanks to hydrophobic nature | ||
Development and testing of photon detectors for 1.5 T
| Baseline: large area HPD of the proximity focusing type | |
| Backup: MCP-PMT |
Photon detector R&D – backup option: Burle MCP-PMT
Photon detector R&D – Burle MCP-PMT bench tests
| Study uniformity of the sensitivity over the surface |
Read-out electronics: ASIC under development
| Gain：5 [V/pC] | ||
| Shaping time：0.15 [μs] | ||
| S/N ：8 (@2000[e]) | ||
| Readout ：pipeline with shift register | ||
| Package : 18 channels/chip | ||
| Proof of principle shown already last time. | |
| More photons: employ radiators with multiple refractive indices. Idea successfully tested in beam tests. | |
| Aerogel production: transmission length improved, new cutting methods tested, multiple layer samples. | |
| R&D issues: development and testing of a multichannel photon detector for high mag. fields | |
| mass production of large aerogel tiles | |
| readout electronics |
| Total number of readout channels for the full detector amounts to 86k. | ||
| Detector characteristics | ||
| Leakage current: 10 or 25［nA］ | ||
| Detector capacitance: 10 or 70 ［pＦ/pixel］ | ||
| signal: 2000 or 20000 [electron/photon] | ||
| Need high density front-end electronics. | ||
| Need high gain with very low noise amplifiers. | ||
| Deadtimeless readout scheme-> Pipeline. | ||
| Develop an ASIC for the front-end electronics | ||
Read-out electronics: ASIC under development
| Basic parameters for the ASIC (Rohm CMOS 0.35μm) | ||
| Gain：5 [V/pC] | ||
| Shaping time：0.15 [μs] | ||
| VGA：1-16 | ||
| S/N ：8 (@2000[e]) | ||
| Readout ：pipeline with shift register | ||
| Package : 18 channels/chip | ||
| Control : LVDS | ||
| Power consumption : 5 m W/channel | ||
| Detailed evaluation is under way. | ||
VA64TAP: backup read-out electronics
Ｐｒｏｔｏｔｙｐｅ Ｔｅｓｔ
- 3×3multi-channel
HAPD -
| Diode : □5 [mm/ch] | |
| Gain : 26000 [electron/photon] | |
| Cd : 73 [pF] | |
| IL : 14 [nA] (average/ch) | |
| Condition: VHV=8[KV], VBIAS=320[V] | |
| In agreement with expectations (+ 6-8 mrad) | |
| Typically around 13 mrad (for 2cm thick aerogel) | |
| Shown as a function of thickness, momentum |
| Shown as a function of momentum, thickness |
PID capability on test beam data
| From typical values (single photon resolution 13mrad and 6 detected photons) we can estimate the Cherenkov resolution per track: 5.3mrad; | |
| -> 4.3sigma p/K separation a 4GeV/c. |
| sq is obtained by fitting the q distribution Gaussian + background |
Yield losses at tile boundaries
| Scan with the beam across the tile boundary. As expected, the yield is affected over a few mm in the vicinity of the boundary. | |
| A simple model (all photons hitting the boundary get lost) accounts for most of the dependence |
| 92% of the surface covered by HPDs | |
| minimal distance between modules: 0.5~mm | |
| max. distance (few mm) allows for feeding in the HV supply cable (has to come to the front side of the HPD) | |
| six equal sectors |