THE LAV PMT PERFORMANCE

Mauro RaggiLaboratori Nazionali di Frascati

Photon Veto WGCern 7/2/2012

On the road to … 1500 blocks! Analysis is based on the database data 18/01/12 So far we have processed a total of 1424 blocks:

of which 1414 good blocks (hoven run)10 blocks have been rejected for HV by hovenNone has been rejected due to rate

The blocks processed are 57.7% of the total The blocks rejected by hoven runs are only 0.7%

(to high HV at equalization 1500)

Block performance PeYPhoto electron Yield Mean = 0.330±0.0013

Sigma = 0.48Photo electron per MeV (MIPs)

Remember that this vale is 50% higher wrt the one for electrons and photons

Block performance HVEqualization high voltage

10%

41%

25%

14%10%

Block High Voltage

1000-1100

1100-1200

1200-1300

1300-1400

1400-1500

Only 10% of blocks have HV higher than 1400 VOnly 10 blocks have HV=1500 V

Rejected blocks

Performance PMT gain

The gain range spanned by 500V increase in HV is rather limited!

Performance Q at equalization

Q response average 4.48 pC Sigma is 0.09 pC only 2%!

Most part of the blocks is within ±0.3 pC <7% equalization.

PEY time stability check

No sizable slope found in the Pey vs time distribution

Different block types analysis

10%

27%

35%

28%

Block Types

11

13

14

15

Blocks are distributed in different ANTI stations. The uniformity in block performance is fundamental to guarantee a good efficiency of the detector.

The data for blocks type 13-14 are final we already processed all of them.

Block types PEYType Mean Pey

11 0.336±0.0070

13 0.329±0.0029

14 0.324±0.0024

15 0.336±0.0027

Maximum difference -3.6% on average PeY

Blocks of type 14 show a bit lower PEY.

Block types Q response The equalization quality is independent from the block type.

The blocks type 15 seem to have slightly lower spread in the charge values obtained by equalization.

Blocks type performance HV

HV in V Type 11 Type 13 Type 14 Type 15

1000-1100 19,1% 12,0% 6,9% 7,8%

1100-1200 46,1% 39,4% 39,9% 41,9%

1200-1300 17,7% 23,3% 27,8% 25,3%

1300-1400 9,2% 13,3% 16,3% 14,9%

1400-1500 7,8% 12,0% 9,1% 10,1%

Distribution of blocks between different HV intervals look quite similar in all block types

Banana database check

Banana 35 is missing

Banana 324 seem to miss 1 block

All the blocks with HV=1500 are currently not assigned to any banana

There is a strange banana number 1789

Conclusion 57.7% percent of block were already in the online

database on January the 18th 2012 The quality of blocks seem stable in time Uniformity of different block types looks very good

The analysis can be refined considering blocks in different LAV stations

The quality of the equalization is excellent