We are fortunate to have a few QuarkNet electronic coincidence cards at our disposal (as long as they continue functioning!!). The cards are very easy to operate once you get around the quirks. This is a guide especially for the Summer Institute and your reference... for a more complete document see the QuarkNet Manual from FermiLab.
Simply plug the card into the 5V power supply, and connect it to the computer. Open 'HyperTerminal' in Windows, which can be found under Programs->Accessories->Communications. Open up a session to 'COM1', the serial port.
The settings for HyperTerminal should be:
Bits per Second: 9600
Data Bits: 8
Parity: None
Stop Bits: 1
Flow Control: None
I've noticed that HyperTerminal complains about some TAPI error on these computers - just click 'OK' to get rid of it, it doesn't seem to matter.
Pressing the reset button on the card (next to the power jack) should cause it to reboot and display the welcome message. We are now ready to go.
Type 'EC' to echo commands... i.e. see what you are typing.
Type 'WC 0E' to 'write control'. This is the command which sets up the coincidence. The two-digit hexadecimal number following the command is a control byte. Laid out in binary it looks like this
|
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
|---|---|---|---|---|---|---|---|
|
Veto select bits: set to 1-3 to indicate a veto on channels 2-4. Channel 1 cannot be used as a veto. |
Set multiplicity of coincidene, from 0 to 3. 1 means a coincidence between two channels. |
Set to enable channel 4 |
Set to enable channel 3 |
Set to enable channel 2 |
Set to enable channel 1 |
||
For example, to enable all channels with no coincidence required, the command would be 00001111... or, in hexadecimal:
WC 0E
To enable channels 1 and 2 with coincidence required, we'd need 00010011:
WC 13
Type DC to display the current control code.
The other command we'll be using is SS/ES
SS surpresses all record of single events, showing only those events with a double pulse in one channel.
ES reverses the supression (enables singles)