MCP Delay Line (Version 6.2.90.5)
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7
Trouble Shooting/FAQ
This chapter contains a collection of questions that are frequently asked by detector users and some answers to it. It also gives
a few hints how to find the cause for real or apparent malfunctions and how to solve or track down the problem.
This chapter is constantly modified and amended. You may find an updated FAQ-list on our web-site
PROBLEM:
“I believe the detector hardware and electronics operate well (all signals have been verified) but
I don’t get data into the computer after starting my “ccf”-file for hardware data acquisition and
…
a)
in the status window the displayed event count rate is zero.”
Verify again if the “start” signal really makes it all the way to the “start” (or “common”) input of the TDC with
proper signal shape (NIM/ECL).
Execute the original “ccf”-file that is used for startup of hardware DAQ as supplied by
RoentDek
.
Is the I/O address setting in the “ccf”-file (
parameter 1
) and on the board correct (any address conflict with
other PC cards possible)?
For
HM1
: Set
parameter 9
to “1” in the “ccf” file and execute it again (only some of the stop signals might be
missing, see below)
For
HM1
: check if the three green LED of the
HM1
are lit. If not, fuses on the
HM1
-I/O board (inside the
PC) must be exchanged.
Are the incoming data not fulfilling the minimum event pattern multiplicity as defined in
parameter 2
?
Are the DAN.dll and DAQ.dll. which correspond to your hardware, in the main
CoboldPC
directory?
Make sure that you have installed the
CoboldPC
program properly. In case of WinNT/Win2000/WinXP OS:
did you log on as ADMINISTRATOR for the installation procedure? Were there any error or warning
messages during installation?
Does your PC meet the hardware specification “US-compatible”?
b)
although the event count rate seems to make sense I don’t get a satisfactorily detector image, at least one
of the time sum spectra does not show a clear prominent peak.”
Verify if all the signals at the inputs just before going into the TDC channels are present and have proper shape
(NIM/ECL). Are they in the right sequence (start before the stops)? Do all the stops arrive?
RELATED QUESTION:
“How can I find out if a certain or which of the “stop” channels is missing without using an
oscilloscope?”
You can check for the presence of the individual stops in the corresponding spectra as defined in the original “ccf”-file from
RoentDek
. For
HM1
: Set
parameter 9
in this “ccf”-file to “1” and execute it again.
PROBLEM:
“The time sum peaks look ok but the 2D image seems not be right compared to what I should
see from my source of incoming particles, there are …”
a)
spots that should not be there.”
These are probably dark counts or there is corona current close to your MCP from a sharp tip emitting electrons or
ions (meshes close to the detector?). To verify possible corona, change potentials on suspicious parts of the setup
and observe if the spots and their rate are changing.
A certain rate of dark counts is normal, sometimes they are concentrated locally, forming minor “defects”. If a local
dark count rate at a defect is higher than 100cts/s contact
RoentDek
. The “normal” dark counts that are acquired
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