The XP2 pulse processor is not a stand-alone unit. It is found in LINK's post-AN10000 systems such as the eXL or ISIS. The XP2 can come with different plug-in cards. We are familiar only with the plug-in card called the PC1934. This is accessible via a removable panel on the LINK system. You should search for the PC1934 connector panel and verify that it contains the connectors described below.

Connections from the SEII to a 3rd party pulse processor are typically made through the external Scanning Interface Unit's DB-25 rear-panel connector labelled PHA Logic I/O. In certain circumstances, a direct connection to the DB-37 connector on the back of a SEII board is allowed. Shown below are the connections that to the best of our knowledge interface the PC1934 to the SIU:

SEII DB37 SIU DB25 XP2 (PC1934) (ADC Busy) 4/22 --->> 2/15 --->> no connection??? (Pulse Reject) 5/23 <<--- 3/16 <<--- definitely no connection (Live Time) 3/21 <<--- 4/17 <<--- Busy (Fast Channel) 2/20 <<--- 6/19 <<--- no connection??? (PHA Input) 6/24 <<--- BNC <<--- Sig Out (no connection) PG (no connection) Reset (no connection) Con (no connection) HV [to preamp] (no connection) Detector [15-pin D connector]

Each signal line has its own ground reference (the pins are listed as signal/ground).

Special Notes:

• We are unable to currently find 4pi customers that still use the XP2, so that we can verify the connections. All have upgraded to the newer XP3 or other systems compatible with 4pi. Therefore, we cannot guarantee the above connections. We strongly recommend that the cable contain the ADC Busy and Fast Channel lines as spares, in case the XP2 is hacked to provide these signals. With the above Sig Out and Live Time signals, you are at least guaranteed to get a spectrum and deadtime information (but no input count information!).
• The XP2 may require an inverted pulse to interface correctly to the SEII board. If so, this can either be done with an inverter of your own design, or by using the SIU v. 2.2 box. Contact 4pi for further details.
• The LINK system is required to be functional and in simultaneous use for our board to correctly acquire data. If your LINK system is down or in disrepair, it is unlikely that the SEII will work.