1. The Totem trigger architecture The LONEG firmware archtecture
XI Pisa Meeting on Advanced Detectors - Isola d'Elba, Italy
The TOTEM Modular Trigger System
M.G.Bagliesia, M.Berrettia, R.Cecchia, V.Grecoa, S.Lamia, G.Latinoa, E.Oliveria, E.Pedreschia, A.Scribanoa, F.Spinellaa, N.Turinia
a) University of Siena and INFN Pisa, Italy
The TOTEM experiment will measure the total pp cross-section with the luminosity independent method and study elastic and diffractive scattering at the LHC. We are developing a modular trigger system, based on programmable logic, able to make, within few thousands of nanoseconds, on-line selection in order to select meaningful events to be stored and later analyzed by off-line algorithms. The trigger algorithm is based on a tree structure in order to obtain information compression. Starting from more than 2000 bits, in a first step we extract 6 bus data of 32 LVDS signals each and then we get a 1-bit decision (L1) and 16 information bits which could be sent to the CMS experiment global trigger system for common data taking in the future.
Abstract
The Totem trigger architecture
Roman Pots (RP): silicon strips at 220 m and 147 m
T1 detector: Cathode Strip Chambers (CSC) at 10m
T2 detector: gas electron multiplier detectors (GEM) at 14m
All three sub-detectors provide level one trigger building signals
The trigger bits for T1 and T2 are transmitted optically, while for the Roman Pots the trigger signals are transmitted electrically (LVDS).
CMS
interaction
point
CMS
cavern
Front
End
Front
End
Front
End
Front
End
Front
End
The T1 detector sends its trigger bits directly to the counting room for further processing, T2 and the Roman Pots make use of programmable coincidence chips, which reduce the number of trigger bits to be transmitted to the counting room by an order of magnitude.
Front
End
Front
End
Front
End
192
bits
480
bits
208
bits
192
bits
208
bits
480
bits
192
bits
192
bits
2000 trigger building bits
VFAT2 chip:
128 channels
Digital output
Hits info
Trigger info (programmable)
Trigger crate
The three TOTEM detectors should be able to operate stand-alone or as sub-detectors of CMS. They need to provide trigger signals which are in time to generate a global trigger for the CMS experiment. TOTEM detectors should be triggered by their general trigger and data should be incorporated into their data acquisition.
COUNTING
ROOM
TOTFED
TOTFED
TOTFED
TOTFED
TOTFED
TOTFED RP
32 bits per pot
768 bits T1
16 bits per detector
960 bits T2
104 bits per quarter
416 bits
The LONEG is:
6 TOTFEDs 32 32 32 32
the final trigger coincidence card
a new mezzanine card, based on Stratix II Altera devices, plugged onto one of the 6 Host Boards inside the trigger crate 32 32
LONEG
1 TOTFED =
1 Host Board +
Mezzanine cards
16 trigger
bits to
CMS
Level-1
trigger
StratixII FPGA
The LONEG firmware archtecture
Host Board
with
LONEG
32 bits Trigger Patterns
From TOTFEDs
Synch
Module
The HOST BOARD
The TOTEM trigger system is a modular device: the main motherboard (known as “Host Board” ) can accept different mezzanine cards, developed ad hoc for different applications.
LUT
Mezzanine cards
Host board functional blocks
Based on Altera FPGA
CMS-Trig bits 16
Link to the other 5 trigger HB
Prescaler
Scalers 16
S-Link
output 16 16 16 or
To CMS
USB 2.0
Level 1
Trigger
LONEG CONNECTIONS
INPUTS
IN-OUT
From each Host Board:
32 trigger pattern bits
1 clock
12 bits bunch-counter
VME interface (local bus)
16 trigger bits to CMS
L1 (NIM and LVDS)
S-Link LSD (92 pin)
OUTPUTS
Hi-Speed USB 2.0
NIM and LVDS
L1 trig out