TIGER documentation

QDC mode

Efine with wrap-around effect explained

The counter for the ADC performing the charge digitization has a wrap-around effect such that very high signals (just below the saturation point) have 1008 < Efine < 1024.

For these values the measurement is still linear, so in order to apply the usual conversion using the calibration line (Efine = const + slope * Qin) we need first to shift them by 1024. Therefore we can define a new variable Efine_new given by:

• Efine_new = Efine (for Efine < 1008)
• Efine_new = Efine - 1024 (for Efine > 1007)

In this way, the values of Efine between (1008, 1023) are shifted to the region (-16, -1) and thus correspond to the very high charge signals, with Efine_new = -16 being the new value of saturation. This is explained in the Figure on the right and the Table below.

Qin	Efine	Efine_new	Description
5	385	385	normal region
10	340	340	normal region
15	295	295	normal region
20	250	250	normal region
20	205	205	normal region
30	160	160	normal region
35	115	115	normal region
40	70	70	normal region
45	25	25	normal region
46	16	16	normal region
47	7	7	normal region
48	1022	-2	wrap-around region, still linear -> apply Efine_new
49	1013	-11	wrap-around region, still linear -> apply Efine_new
50	1008	-16	saturation
55	1008	-16	saturation
60	1008	-16	saturation

Rate considerations

TIGER

CGEM-IT setup:

• clock frequency = 160 MHz
• 2 Tx links per chip running at 160 MHZ SDR (Single Data Rate)

Chip maximum bandwidth = 320 Mbit/s

1 event word = 64 bits --> 80 bits with 8b/10b encoding

Chip maximum rate = 320 Mbit/s / 80 bit/event = 4 M event/s = 4 MHz

Channel maximum rate = 4 MHz / 64 channels = 62.5 kHz per channel

Frameword rate = 4.8 kHz per chip (equivalent to 76 Hz per channel increase)

GEMROC

TRIGGER-MATCH

Assumptions:

• 25 kHz rate per channel (noise + physics)
• 1.5 us time window
• 8 TIGER (512 channels)
• Two 64-bit header and trailer words for GEMROC packet
• Maximum L1 trigger frequency = 4 kHz

25 kHz per channel --> 1.6 MHz per chip

Number of hits per trigger = 1.6 MHz * 1.5 us = 2.4 hit/packet

Average packet size = 2.4 hit/packet * 64 bits (event word size) * 8 (TIGER) + 2 (header+trailer) * 64 bits = 1228.8 bits + 128 bits = 1357 bits = 170 bytes

Maximum trigger-matched data rate = 170 bytes * 4 kHz = 680 kB/s = 5440 kbit/s per GEMROC

TRIGGER-LESS

Assumptions:

• 25 kHz rate per channel (noise + physics)

25 kHz per channel --> 1.6 MHz per chip

Trigger-less data rate = 1.6 MHz * 8 (TIGER) * 64 bits (event word size) = 819.2 Mbit/s = 103 MB/s per GEMROC

DAQ PC

1 GbE link

Maximum bandwidth = 1 Gbit/s = 125 MB/s

• Can easily accomodate data from more than 20 TM GEMROC modules
• Can only accomodate data from 1 TL GEMROC module

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