Log entry time 17:07:42 on March 06, 2011

Entry number 350576

This entry is a followup to: 348457

Here are additional details on the EDTM timing setup and measurements I
made for HAND on Feb. 24th.

edtmsetup [LDELAY] [RDELAY] [BBDELAY] [HDELAY]

1) [BBDELAY] was set to 232 (in units of 2.2 ns) or 510 ns, which 
represents a 300 MeV/c proton into BB at a 3.5 m distance.  

2) HDELAY was set to 24 ns for a total of BBDELAY+HDELAY = 534 ns for a 
488 MeV/c neutron into HAND.  Note this was for the first efficiency 
measurement try last week (Feb 23-24).  

3) LDELAY was set to 0, since it detected the electrons.

4) RDELAY was set to 112 (44+68), where 44 is the intrinsic delay between
the arrival of the EDTM pulse in the left and right HRS, i.e., the right
arm pulse arrives earlier due to a shorter delay cable.  The TOF 
difference between left and right was 101 ns for a 3.114 GeV/c electron
and a 0.488 GeV/c proton with S2m in the trigger.  To get the correct
timing on the EDTM for the right arm, I added an additional 29 ns of 
cable delay for a total of 141 ns.  

On Feb. 23rd the T3 delay was set to 72 ns.

Relevant numbers for HAND:

ADC gate width: 400 ns
EDTM injection point (discriminator) to gate: ~ 500 ns
ADC cable delay: 560 ns

I then measured the time difference between when T3 reaches the weldment
and T7 is formed = 162 ns (before any cable delay is added).  The 
expected time difference between forming T3 on HRS and sending to the
weldment and right before the HAND PMTs signals reach the discriminators
is 147 ns (so very close).

I then sent the edtm pulse through the ADC delay to mimic an ADC signal
through veto 1R.  I found that the EDTM signal showed up about 56 ns 
after the gate that is sent to the ADC.  There is additional cable delay
for both the gate and ADC signals before the actual modules, but I do 
not expect a change of more than 20 ns between them.

Finally I measured the EDTM signal wrt the common stop (same as the
ADC gate), the injected EDTM came about 450 ns before the stop.  The 
actual TDC signal would be a bit closer due to the cable length to
transport the stop to the back of the Fastbus crate.

On Friday, Feb 25th, I removed 30 ns of delay to the gate/stop for HAND,
since there was evidence that the gate was clipping the PMT pulses for 
the ADCs.