Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 47 (2014)

RIKEN Accel. Prog. Rep. 00 (0)Common trigger firmware for GTO
H. Baba,∗1 T. Ichihara,∗1 T. Ohnishi,∗1 S. Takeuchi,∗1 K. Yoshida,∗1 Y. Watanabe,∗1 S. Ota,∗2
and S. Shimoura∗2
The data acquisition (DAQ) system at RIKEN
RIBF1) utilizes the ﬁeld programmable gate array(FPGA)-based logic modules of LUPO2) and GTO3) .
A common trigger ﬁrmware for the GTO has been introduced for experiments in BigRIPS, SHARAQ, EURICA, MINOS, and SAMURAI4) . There are two versions of the common trigger ﬁrmware: 8-trigger/16end-of-busy inputs version and 4-trigger/20-end-ofbusy inputs version. Both versions provide the samefunctionality, and the only diﬀerence between them isthe number of the trigger and busy inputs. Here, wereport on the functionality and timing performance of
the 8-trigger/16-end-of-busy inputs version of the common trigger ﬁrmware.
This ﬁrmware was developed to provide acceptable
triggers, i.e., the common trigger, for all CAMAC andVME front-end systems. Previously, three logic fanin/out, three latch and one coincidence NIM modules were used to generate the common trigger. However, the developed ﬁrmware can generate the common trigger using only one GTO module. In addition, the remote control capabilities via Ethernet of
the GTO allow us to change the trigger conﬁguration without inserting and removing cables. Commontrigger ﬁrmware consists of trigger multiplexer, multichannel latch, and trigger veto circuits. Figure 1 shows
the functional schematic of the ﬁrmware. The trigger
multiplexer circuit has 8 inputs, and these input signals are enabled by the remote control function. The
multi-channel latch circuit produces the veto signal forthe trigger when CAMAC/VME front-end systems arebusy. There are 16 end-of-busy inputs; therefore, thisﬁrmware can accept up to 16 CAMAC/VME front-end
systems. Each latch signal is triggered by the leadingedge of the accepted trigger, and it is cleared by thetrailing edge of the end-of-busy signal from the frontend system. The trigger veto circuit inhibits trigger
signals when either DAQ is not started or at least oneof the front-end systems is busy. Using these circuits,
the GTO can provide the complete common trigger.
The dead time of the DAQ system is determined by
the slowest front-end system.
To evaluate the timing performance of the commontrigger ﬁrmware, the propagation delay and time jitterare measured. The propagation delay is the time between the trigger input and the accepted-trigger output. These parameters are measured by an Agilent
Technologies U1060A-002 TDC, which has a timing
resolution of 5 ps; the results are shown in Tab. 1.
∗1∗2

Trigger Veto

Ch1
Ch2

AcceptedTrigger

Ch3

Latch

EOBstart
stop

EOB

start
stop

Latch

DAQ start/stop

Fig. 1. Circuit schematic of the common trigger firmware.
EOB is end-of-busy signal from the front-end system.

Table 1. Propagation delay and time jitter.
Channel
1
2
3
4
5
6
7
8

delay (ns)
15.7
15.9
15.5
15.9
16.2
16.1
16.5
15.8

jitter (ps)
66
7
4
7
68
5

According to these results, the skew, that is, the maximum diﬀerence between the propagation delay of allchannels, is 1.0 ns. This 1.0-ns skew is not small but
does not present any diﬃculty to the function of thetrigger multiplexer. The maximum time jitter is 8 ps,
which is normal for a NIM logic module.
In summary, the common trigger ﬁrmware for theGTO has been successfully developed. It allow us toreduce the number of logic NIM modules and change
the conﬁguration remotely. Further, the timing performance of the ﬁrmware is suﬃcient for use as a trigger
circuit.
References
1) H. Baba et al.: Nucl. Inst. Meth. A 616, 65 (2010).
2) H. Baba et al.: RIKEN Accel. Prog. Rep. 44, 213(2011).
3) H. Baba et al.: RIKEN Accel. Prog. Rep. 46, 213(2013).
4) H. Otsu et al.: RIKEN Accel. Prog. Rep. 46, 146 (2013).

RIKEN Nishina Center
Center for Nuclear Study, University of Tokyo- 235 -1