Triggering with the RPD

E. Burtin, CEA-Saclay

COMPASS Hadron run trigger meeting, Feb. 12, 2008

Overview of the full project

Ring A

Ring B

Commissioning

Calibration (Oct 12 - Nov 5):rot 0°, 30°, 90°Trigger tests (Nov 5 - Nov 11)

6 7

View fromJura side 2007Upstream 2008

9

56

8

Ring A

18

1

2

58

10

11

12

13

14

15

161719

2021

22

23

43

0 01

2 3 4

7910

11

Ring B

Muonbeam 0

54

3

2

1

6

7

Energy loss correlations

Tests in 2001

protons

protons

-electronsThicknessA : 4 mmB : 5 cm

ThicknessA : 5 mmB : 1 cm

Trigger condition

protons

e

Area of interest is :Ahi.Blow or Alow.Bhi

Alow

Bhi

Ahi

Blow

Thresholds choice ingredients: - Dynamical range - Attenuation (=70cm) A : 0.25 B : 0.10

Limitation on Bhi to accept high momentum (1GeV/c) proton

Proton identification

protons

e

275 410 760 MeV/cFor protons

Limitation:Thickness of Bring elements

Proton trigger

Trigger timed on Alow

down

Trigger:- At least one A.B pair fired - Done- Only one A.B pair fired - Under study

Jitter on signals

tupB

tdoB

tupA

zB tB

tdoA

zA tA

target Z

LB

LA

tdoA has ~2ns jitter

Leading edges of all signals within 30ns

Trigger board : CAEN V1495

Design & Programmation of the FPGA done by Christophe Flouzat« Conduct of operations » :

• All signal sampled at 400 MHz (2.5ns)• Individual delays applied• Logic function realized• Output of signals on 2 lemo & 64 LVDS

Ai;downlow

Ai;uplow

Bihi

Trigger

80ns

D

D

D

Could fit in 50 ns

Trigger latency

Adownlow

Trigger

Time to produce a trigger < 150 ns

Laser signal

Trigger signal jitter with BEAM

Oscilloscope triggered by the finger trigger signal

Scope triggeredby hodoscopes signals

Conclusions

Trigger board :• Design validated

• Jitter of AiBj coincidence is ~2.5 ns (due to the sampling)• Each coincidence can be aligned in time

Open possibility• 32 spare inputs for Forward Hodoscopes if needed• 64 outputs can be used for further processing

Needs commissionning with beam …