A Beamsstrahlung Monitor
tentative and provided for informational reasons.
The LABM rates and currents are as follows:
- Documentation on desired features:
A) There are 32 channels, initially each connected to a PMT;
B) Later connected to a Si-PMTs (incidentally, I have ordered
Si-PMTs, and I will send you four as soon as they arrive).
1) Initial SuperKEKB phase, with beam intensities 1/10 of nominal,
2) Nominal SuperKEKB conditions, Si-PMT, 5760 pixels per
- Photon Rates: 0.1 to 0.01 per bunch crossing (6 to 0.6 MHz
- Gain for most PMTs at our common mid-plateau point is between
1 and 1.5X10^6
- PMTs have a measured rise time of 4 nsec and decay time of 10
I note that we expect to run on PMTs for a couple of years, so that
your costing could very well be done on PMT electronics alone.
Photon rates 100 to 10 per crossing, hit rates are 5GHz to 500
- Gain is close to 10^5 (from Advansid)
- Rise time is 1 nsec or below, decay time is 100 nsec
- The signal will probably need
to be differentiated.
In other words,we will be busy with detector
calibration, studies of total rates, and correlations with other devices.
- I think that, for
the first two years, I will want to see the same information that John Flanagan
wants to see, rate-wise.
His device, too, has limited bunch-following capabilities, and when it comes to
correlation studies we
are only as fast as the slowest device.
EPICS will allow us to broadcast
rates at 10Hz,
but no more.
- It has become clear
to me that, initially, we will be entirely dependent on EPICS for data analysis.
I also suggest that we ignore
signal differentiation for the time being. By the time we will be in
need to differentiate, we will have clear ideas
of which kind of electronics we
So, to conclude:
differentiation for the early electronics
2) 10 Hz
3) I can
not remember how many bunches John can follow at any given time,
but I think
he can follow only one at a time. That would be suitable for
My only doubt is that people
may want to test early this device against
the BPM system, which is
designed to work at 1kHz from day one (so I have
doubts only about 2), plus I
need to be precise about 3)). I will talk to
John about it next week and
report promptly to you.
GSV's initial thoughts:
While it may be true that comparison of a sub-set of the
data with the XRM only requires modest input,
it may be possible to utilize the RITC
chip and hardware histogramming to build a fuller picture
of the entire orbit.
Nov. B2GM meeting time may be a good opportunity.
[UH Physics] [University of Hawaii]
Last modified: 11/13/2011