CFDBCN meeting December 2003

1
CFD-BCN meeting December 2003

• Eugeni Graugés
• on behalf of the
• Barcelona LHCb groups

2
Hamamatsu Multi-Anode PMT choice

• SPD typical signal/current 100 fC/m.i.p (maximum)
• The number of SPD photo-electrons depend on
• Different PAD sizes
• Scintillator Response / Aging
• Light collection efficiency
• Light transport efficiency / Fiber ageing
• Range 10-40 p.e. / m.i.p gt
• Gain range of 64 k 16 k Range

3
6-stage PMT

• Voltage Divider Scheme 3-2-2-1-1-2-5
• Maximum Inter-dinode Voltage 250V
• Maximum working HV 800 Volts
• Gain Range
• lt50k _at_ HV 800 Volts
• 5k _at_ HV 600 Volts
• Does not cover the gain dynamic range

4
6 Stage PMT

• Voltage Divider Scheme 3-2-2-2-2-2-2
• Maximum Inter-dinode Voltage 150V
• Maximum working HV 750 Volts
• Gain Range
• 70k _at_ HV 750 Volts
• 30k _at_ HV 600 Volts
• At limit, with no room to recover from
  statistical dispersion and tube ageing

5
8 Stage PMT

• Standard Hamamatsu Voltage Divider Scheme
  3-2-2-1-1-1-1-2-5
• Covers the dynamic gain range with a safety
  factor of 2 to recover from ageing and
  statistical tube dispersion (see data-sheet)
• OK for the SPD

6
8 Stage PMT

• New recommended Hamamatsu Voltage Divider Scheme
  
• 2.4-2.4-2.4-1-1-1-1-1.2-2.4
• Maximum Inter-dinode Voltage 150V
• Maximum working HV 925 Volts
• Gain Range
• 300k _at_ HV 925 Volts
• 5k _at_ HV 500 Volts
• It has an additional 2.5 safety factor to the std
  Hamamatsu scheme OK for the SPD

7
12 Stage PMT

• Standard Hamamatsu Voltage Divider Scheme
• Covers the dynamic gain range with enough room to
  recover from ageing and statistical tube
  dispersion (see data-sheet)
• OK for the SPD

8
Conclusions

• 6 stage PMT with the CFD suggested voltage
  divider at the edge of covering the gain dynamic
  range, for the only tested tube. It leaves no
  room for recovery from ageing and statistical
  tube dispersion
• 8 stage PMT Hamamatsu std is OK for the SPD
  (factor 2 of safety), and still better with the
  new suggested voltage divider (factor 2.5 extra)
• 12-stage PMT Could be OK for the SPD too, but
  probably not suitabel for the PS