General

Beam line data is taken with "common trigger" + "common dead time" mode. User CAMAC/VME FECs (front-end computers) can join beam line DAQ. In this case, trigger is distributed from BigRIPS measurement room to all. All FECs must send CAMAC/VME busy-end signal to BigRIPS measurement room.

Individual trigger and non-common dead time are available. In this case, the time stamping system is required. There are CAMAC and VME time stamp modules based on LUPO. LUPO (Logic Unit for Programmable Operation) is a FPGA-based general purpose logic module, developed by H.B.

Common trigger + common dead time

To get the best live time, the common trigger + common dead-time mode is used. It is necessary that keeping the strict common trigger, dead-time sharing between FESs is necessary. The logic OR of all DAQ busy is used as the veto signal for the common trigger. This veto signal is generated by standard latch and logic OR modules. The FEC having the longest DAQ busy determine the system dead time. With a scaler module, the system live time (dead time) is calculated from the number of the ungated (generated) trigger and gated (accepted) trigger.

For BigRIPS and ZDS beam line, there are 1.5us optical delay cables for all plastic and PPAC detectors not only for timing but also for analog. These long delay cables are useful for making the common trigger coincident with additional detectors (sush as a gamma ray detector array).

Individual trigger (Time Stamp)

Individual trigger and the time-stamp based event building system is available. The clock synchronization between other DAQ (trigger) domains is required. This synchronization is done by newly developed time-stamp module based on FPGA. This time-stamping system has been working for SHARAQ and beta-decay experiments. If you need the time-stamping system, please contact us long before the experiment.

Optical cables (measurement rooms - experimental rooms)

These are rough values. In addition to these optical cable delays, there are delays between detectors and NIM racks. Timing delay calculator including the beam energy will be prepared in the near future.

BigRIPS

B3F - F1  141m (715ns)
B3F - F2  124m (620ns)
B3F - F3  106m (530ns)
B3F - F4   87m (435ns)
B3F - F5   75m (375ns)
B3F - F6   61m (305ns)
B3F - F7   48m (240ns)
B3F - F8   31m (155ns)
B3F - F9   63m (315ns)
B3F - F10  54m (270ns)
B3F - F11  61m (305ns)
B3F - F12  34m (170ns)

Until April 2010, F9,F10,F11 were shorter than 10m than this list.

SHARAQ

SH B3F - HF7  50m (250ns)
SH B3F - HF8  60m (300ns)
SH B3F - HF9  65m (325ns)
SH B3F - HF10 65m (325ns)
SH B3F - S2   90m (450ns)