SoLID EC PMT meeting

• 4/17-4/18/2014
• R11102:
  
• need transistors to stablized dynode HV
• Typically, need anode current >5% of divider current. If we run at an average anode current of 10uA, a 1mA-HV power supply is more than enough.
• At a gain of 2E5, our expected electron max amplitude is 42mA. To keep this value below the +/-2% linearity limit of 10mA as in R11102 datasheet, we need to run at a PMT gain of 5E4. In this case, a preamp gain of (3-5) is preferred.
• Should we try to power more than 1 PMT from one HV power supply? -- V.P.: too troublesome for gain matching during the experiment, suggest no, but can re-visit this question later.
  
• Preshower: We will focus on 16-ch MAPMT. 
• The 64-ch MAPMT will require a preamp gain of 150. VP: 150 is too much. Typically a 10-20 preamp gain can be done reliably. Can push for 50 if needed. We will therefore focus on the 16-ch MAPMT option.
  
• 16-ch MAPMT: linearity (+/-2% at 1.2mA) is not a problem.
  
• For 16-ch preamp, should provide a separate LV power (in the range of +/-5V-+/-10V).
• With the preamp powered by a separate LV input, can use the standard Hamamatsu (built-in) HV divider without modification.
• Need to test preamp cross-talk.
• The PMT gain will be 2E4, which requires very low HV. Need uniformity table for this low HV range from Hamamatsu. Detector group can aloso test this, but probably won't be exactly the same results.
• SPD:
  
• The requirement on SPD photon rejection is not very crucial, thus we could focus more on a more cost-effective design. 
• VP: For small signal, a threshold of 20mV is minimal (comfortable).
• If we use R8619 and run it at 5E5 (anode current average at 10uA), will need a preamp gain of 20. VP suggested we could also use R9800 for which Hall D already have a working divider with preamp. (XZ: R9800 is slightly more costly but the specification does meet our need).
  
• We can also use a 16-ch MAPMT. If we limit preamp gain at 50 then will need to run the PMT at a gain of 1E5 (average anode current at 32uA). Can still work. The advantage is that we can probably combine this with Preshower and use the same 16-ch MAPMT.
  
• The Minova experiment will have many 16-ch MAPMT available by the time we run SoLID. Thai will get the MAPMT model information soon.
• Xiaochao will inquire on the 16-ch MAPMT cost from Hamamatsu. Will send one R11102 tube to JLab when available.
  
• And updated requirement table, adopted from the 3/26/14 EC meeting minutes:

• Detector	SPD	Preshower	Shower
  PMT option (current)	16-ch MAPMT R11265-100-M16 (or Minova option, see notes above). R11265 datasheet	16-ch MAPMT R11265-100-M16 (or Minova option, see notes above). R11265 datasheet	R11102: datasheet, drift
  average anode current with G the PMT gain	I = G*(2E-11A/ch)	I = G*(7E-11A/ch)	I = (G*5E-11A/ch)
  MIP pulse current assuming 30-ns triangular pulse	G*0.1nA	G*0.32nA	G*6.2nA
  max (electron) pulse current assuming 30-ns triangular pulse	N/A	G*(12.8nA)	G*(0.21uA)
  PMT gain G to be used, and reason	1.6E5, to keep required preamp gain <=50, such that half MIP (threshold) is at 20mV	1E4, to keep anode current below 10uA (sum of 16 channels, or each channel <0.62uA)	5E4, to keep max electron pulse below the 2% linearity limit of 10mA
  PMT HV for the desired gain	~750V if using R11265 (middle of Hamamatsu datasheet HV range)	~560V if using R11265 (lower end of Hamamatsu datasheet HV range but not off-chart)	~620V (lower end of Hamamatsu datasheet HV range but not off-chart)
  running condition with desired gain	average anode current: 3.2uA/ch, 51.2uA total; MIP pulse peak: 16uA or 80uV	average anode current: 0.62uA/ch, 10uA total; MIP pulse peak: 3.2uA or 0.16mV electron max pulse peak: 0.128mA or 6.4mV (dynamic range ~40)	average anode current: 2.5uA; MIP pulse peak: 0.3mA or 15mV; electron max pulse peak: 10mA or 0.5V
  Preamp gain, and reason	50, highest pre-amp gain that we are comfortable with	50, highest pre-amp gain that we are comfortable with. Will fill up to 0.32V of FADC. If filling the full 0.5V range is desired, can run at 15% of max anode current.	4 (4 will fill the full 2-V range of FADC).
  Other information	HV board is planned to be the CAEN 1535A floating 3.5kV/3mA(8W)