Structure of the list-mode-data written by MBS

Data acquisition setup for measuring the photon production cross section

One List-Mode-Data (LMD) readout event contains several trigger events. The number of these trigger events depends on the v1495_trig_scal, read_till_end and repeat_readout values in the setup.ini file. Typical values range from 1 up to 512. The actual maximum number of trigger events has to be checked while reading out the LMD file to avoid array overflow.

The event structure depends on the electronics schema used but consists of a number of 32 bit long data words. The type of word is identified by the 5 highest bit the so called GEO. Depending on this GEO the meaning of the different lower bits is shown in the list below.

The single Data words have the following bit-structure:

Time:

GEO = 0
31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	0	0	0	0	0/1	Time / 100 ms

Bit 26 is 0 for real time and 1 for live time

real and live time are written once only after the stop acquisition signal (trigger type 15) as an end of acquisition flag

Time Flag:

GEO = 1
31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	0	0	0	1	Scaler period / ms

The time flag is written as a header for the scaler data block and gives the time between each scaler readout

Scaler Values:

GEO = 4
31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	0	1	0	0	N = number of scaler words following

Subsequent to this single data word N further words are following. Each word contains only one 32 bit value. The meaning of each value is the number of hits counted by the scaler. Note that each scaler channel can be used in scaler or timer mode. In scaler mode the number of rising edges of the input signal are counted. In timer mode the integrated time when the input is high is measured by creating the conjunction of input signal and the internal clock.

consecutive number = scaler ch	Value
0	OR of FPGA input 00-07
1	OR of FPGA input 08-15
2	OR of FPGA input 16-23
3	Coincidence Pl 0
4	Coincidence Pl 1
5	Global OR
6	raw trigger
7	vetoized trigger
8	downscaled trigger
9	FPGA clock
10	FPGA clock AND veto
11	FPGA clock AND NOT veto
12	N.C.
13	veto (timer)
14	not veto (timer)
15	1 (timer)
16	ADC words
17	ADC events
18	QDC1 words
19	QDC1 events
20	QDC2 words
21	QDC2 events
22	TDC words
23	TDC events
24	veto words
25	veto events
26	LMD words
27
28
29
30
31	target changes
32	FC channel 1
33	FC channel 2
34	FC channel 3
35	FC channel 4
36	FC channel 5
37	FC channel 6
38	FC channel 7
39	FC channel 8
40	LaBr3 1
41	LaBr3 2
42	LaBr3 3
43	LaBr3 4
44	LaBr3 5
45	HPGe 0
46	HPGe 1
47	HPGe 2
48	HPGe 3
49	HPGe 4
50	PTB FC
51	Accelerator
52	SOR (start of readout)
53	TDC gate
54	ADC gate
55	QDC1 gate
56	QDC 2 gate
57
58
59
60
61
62
63

for the DAQ channels cf. cabeling scheme

Veto scaler:

GEO = 6
31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	0	1	1	0	N = number of veto length values following

Subsequent to this single data word N further words are following. Each word contains only one 32 bit value. Note, that the order of the bytes of these words has to be swapped. The meaning of each value is the length in units of 25 ns of the following signals:

consecutive number	Signal
1	ADC Busy
2	QDC 1 Busy
3	QDC 2 Busy
4	DAQ total dead time
5	Trigger length
6	Veto (total event dead time)

TDC Data:

GEO = 8					1
31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	0	0	0	1	Channel					Measurement

TDC Channel	Input
0	FC 1
1	FC 2
2	FC 3
3	FC 4
4	FC 5
5	FC 6
6	FC 7
7	FC 8
8	LaBr3 1
9	LaBr3 2
10	LaBr3 3
11	LaBr3 4
12	LaBr3 5
13	HPGe 0
14	HPGe 1
15	HPGe 2
16	HPGe 3
17	HPGe 4
18	PTB FC
19	N.C.
20	N.C.
21	N.C.
22	N.C.
23	N.C.
24	Accelerator
25	N.C.
26	N.C.
27	N.C.
28	TDC trigger
29	trigger
30	veto = veto start
31	not veto = veto end

for the DAQ channels cf. cabeling scheme

TDC Trailer:

GEO = 8					0
31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	0	0	0	0					Status						Word counter

Trigger Time Tag:

GEO = 9
31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	0	0	1	Time since previous trigger / 800 ns

ADC/QDC Header:

GEO = 10, 12, 14					2
31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	0	1	0	0	1	0	Crate no.										memorized Ch.

ADC/QDC Data:

GEO = 10, 12, 14					0
31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	0	1	0	0	0	0				Channel			Range				UN	OV	Measurement

Range = 0 is for the low gain value, 1 for high gain UN = 1 indicates that the value was below the programmed threshold OV = 1 indicates a dynamic range overflow

Channel	ADC (GEO = 10)	QDC 1 (GEO = 12)	QDC 2 (GEO = 14)
0	HPGe 0	FC 1	LaBr3 1
1	HPGe 1	FC 2	LaBr3 2
2	HPGe 2	FC 3	LaBr3 3
3	HPGe 3	FC 4	LaBr3 4
4	HPGe 4	FC 5	LaBr3 5
5	PTB FC	FC 6	N.C.
6	N.C.	FC 7	N.C.
7	N.C.	FC 8	N.C.

Target Change Flag:

GEO = 28
31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
1	1	1	0	0																											new Target