The CLEO-c Trigger System: More Than Just Blinking Lights ! LEPP Lunch Talk Mats Selen

M. Selen, 7/24/03 LEPP Lunch: Pg 1www.hep.uiuc.edu/cleo/trig3/

The CLEO-c TriggerThe CLEO-c Trigger System:System:More Than Just Blinking Lights !More Than Just Blinking Lights !

LEPP Lunch Talk

Mats Selen

Overview Tracking Calorimeter Timing Performance


What the Trigger & DAQ DoesWhat the Trigger & DAQ Does

Suppose you want to keep only pink hexagonal widgets moving down a conveyor belt.

y/n

y yn n

Trigger

You are the trigger: You stamp “y” on the pink hexagonal widgets You stamp “n” on the others

n

y

trash

SAVE

DAQ

Your friend DAQsaves only widgetslabeled “y”

The problem is: Working fast means you make some mistakes !


Requirements: Decision TimeRequirements: Decision Time

Each widget must get examined and stamped

y/n

y yn n

Trigger

- You need to decide on one before the next one comes along.

- Your decision can’t take longer than t = d/v.

- Taking more time means making less mistakes.

v

d


Requirements: EfficiencyRequirements: Efficiency

You can’t stamp too many pink hexagonal widgets ”n”:

y/n

n nn n

Trigger

SAVE

DAQ

nn n

trash

?? ?


Requirements: RejectionRequirements: Rejection

y/n

y yy y

Trigger

The rate of widgets stamped “y” can’t exceed the capacity of your friend (the DAQ) to save them.

y

trash

SAVE

DAQ

y

Whenever the DAQ is busy saving something it causes “dead-time” (he will miss the next few widgets). If he misses any marked “y”, thiscauses a loss of efficiency.


y/n

Working in Steps: PipeliningWorking in Steps: Pipelining

Have more than one person working in series

- Each individually one takes less than t = d/v- Collectively, much more work is done- A smarter decision can be made – less mistakes

y yn n

Trigger

n

y

trash

SAVE

DAQ

v

d



14 feet

800 feet

d = 14 feet, v = 1 foot/ns

t = 14 ns

There are 183 RF buckets in CESR


The trigger runs at1/3 the CESR RF freq

(i.e. each step is 42 ns)

This smears together 3 beam collisions every time we look. We can do this

since its very rare that anything happens during a collision.

In CESR/CLEO, beam collisions are

spaced a minimum of 14 ns apart.

This is not enough time to do any serious trigger processing

Only ~45 of thesebuckets contain beam ‘bunches’


0 1 2 3 . . . . . . 58 59 60

0

1

2

3

60

59

58


0 1 2 3 . . . . . . 58 59 60

0

1

2

3

60

59

58


0 1 2 3 . . . . . . 58 59 60

More about thisin a few minutes


Trigger Philosophy Use only drift chamber (DR) and calorimeter (CC) information. Make trigger decision every 42ns (i.e. trigger clock rate). Take enough time (number of pipelined steps) to make a sophisticated Level-1

trigger decision: About 2 s. The readout deadtime is about 20 s, so we need to keep the trigger rate < 1000

Hz.

RF bucket

Pipeline clk

Early DR

Late DR

Early CC

Late CC

look here for CC info

72 MHz

24 MHz

look here for DR infoSuppose eventhappens here


TRCR

Mixer/ShaperBoards

TILE(8)

ASUM

QVME

TILE (16)

ASUM

AXTR(16) AXX(16)

DR3 - TQT

STTR(12)

TRCR

L1D

G / CAL

DFC

CLEO

An

alo

g

Gates

ctrl

.

Mixer/Shaper Crates (24)

QVME

TPRO(2)

TCTL

TIM

DM/CTL

TIM

DM/CTL

TIM

DM/CTL

TPRO(4) TIM

DM/CTL

TIM

DM/CTL

AXPR

CCGL

SURF

SURF

Drift Chamber Crates

Axi

al t

rack

erS

tere

o t

rack

er

Bar

rel C

CE

nd

cap

CC

CC

Dig

ital

Lev

el 1

dec

isio

nF

low

co

ntr

ol &

Gat

ing

DAQ

CLEO-III/cTriggerSystem

Overview


What it Looks LikeWhat it Looks Like (all more or less alike to untrained (all more or less alike to untrained

eye)eye)


Common FeatureCommon Feature

FPGA based Logic

DAQ/VME

CircularBuffer

Inputs Outputs

TDITMSTCK

TDO JTAG


16 AXTRtrigger boards

backplane(single ended)

16 AXX receiver boards

LVDS fromDR3 preampstrack info to

TRCR

106 x 2Repeatingunit (x 8)

7

Axial Tracking TriggerAxial Tracking Trigger


Layer 9 = “key”

InnerLookup

OuterLookup

Inner/Outer track correlator


Stereo Stereo Tracking Tracking TriggerTrigger

There are too many wires to form allcombinations in LUT

- Combine these into 4x4 blocks


r

TQT

48

TQT

48

8

8

8

stereo trigger hardware

8

1 superlayer


= Hit wire location at z = 0

Track trajectory:Pperp = 350 MeV/c = 35o

= 15o

-shifted curve, Pperp = 350 MeV/c = 35o

= 17o

Track in U and V IndependentlyTrack in U and V Independently


Axial – Axial – Stereo Stereo

CorrelationCorrelation


Axial – Axial – Stereo Stereo

CorrelationCorrelation


Axial112

112

48

Raw key wires

Clustered key wires

Axial matching cells

48 high

48 low

Stereo - U

48 high

48 low

Stereo - V

Axial - Stereo CorrelationAxial - Stereo Correlation

high highlow


Calorimeter TriggerCalorimeter Trigger

Energy sharing between boardscan result in a loss of efficiency:

Present summing = Tile summing =

Sim

ula

ted

E

ffic

ien

cy

containedshower

Threshold = 500 MeV


Wrinkle – We need to work fast!Wrinkle – We need to work fast!

Preamp out

Mixer/shaper out

Trigger signal

Discriminator out

2 s/div

Calorimeter trigger informationcomes ~ 1.8 us after crossing.

twicedifferentiated


1 m/s crate

1 m/s card

lowmed

high

“Tiling” sets too many bits Must Sparsify


H M L proj

01

11

11

10

11

H

M

L

proj 11

11

10

01

H

M

L

011

001

001

lowmed

highAvailable

to decisionboards


10

Key

Wir

e

Time Bucket

20

30

40

50

60

70

80

90

100

110

5 10 15 20

#trackEv-time

Timing IssuesLOW

MED

HIGH

CC time – TR time


0 1 2 3 . . . . . . 58 59 60

That’s how thisplot is made !


Compare to Simulation

(1995)

Mean = 17.5RMS = 0.73

Mean = 16.9RMS = 0.51

Mean = 16.7RMS = 0.41

Mean = 16.6RMS = 0.37

1 track events 4 track events

7 track events 10 track events

Trigger Time (42ns bucket) Trigger Time (42ns bucket)

Trigger Time (42ns bucket) Trigger Time (42ns bucket)


Pipe-delay

Fro

m A

XT

R

MAKE 48MATCHINGCELLS

Bac

k-pl

ane

Pipe-delay

FINDEVENTTIME

Pipe-delay

AXIALCELLCOUNT

CB & DAQ

Typical Trigger Board

For timealignment


AXPR

TRCR-1

TRCR-2

CCGL

L1D

From AXTRCrate

From STTRCrate

From TPROCrate

To DAQ

L1D Trigger Crate

LUMI


LUT

8 FPGAs

Timing (3)

Info (185)

Timing (TR, CB or CE)

Info (valid at timing edge)

Route48 Prescale24 Bunch24

Scaler

L1-accept

Bac

kpla

ne

Trigger Decision Boards (L1D)Trigger Decision Boards (L1D)


How To Define How To Define a CLEO-c a CLEO-c

Trigger LineTrigger Line

% Generic Hadron Line, Barrel Timing%SUBDESIGN line0(

in[117..0] : INPUT;out : OUTPUT;

)

Variable1cblow : SOFT;3tracks : SOFT;evtime : SOFT;

Begin-- trigger bit mappings:

tr_time[1..0] = in[1..0];cb_time[1..0] = in[3..2];ce_time[1..0] = in[5..4];cc_time[1..0] = in[7..6];

tr_n_hi[3..0] = in[11..8];tr_n_lo[3..0] = in[15..12];tr_n_ax[3..0] = in[19..16];tr_lowpos[1..0] = in[21..20];

cb_l_phi[7..0] = in[29..22];cb_h_phi[7..0] = in[37..30];

cb_low_old[1..0] = in[39..38];cb_med_old[1..0] = in[41..40];cb_high_old[1..0] = in[43..42];ce_low_old[1..0] = in[45..44];ce_med_old[1..0] = in[47..46];ce_high_old[1..0] = in[49..48];

cb_n_low[2..0] = in[52..50];cb_n_med[2..0] = in[55..53];cb_n_high[2..0] = in[58..56];ce_n_low[2..0] = in[61..59];ce_n_med[2..0] = in[64..62];ce_n_high[2..0] = in[67..65];

bha_theta[7..0] = in[75..68];

cc_spare[15..0] = in[91..76];

cpu_trig[1..0] = in[93..92];

control[23..0] = in[117..94];

------------------------------------------------ trigger line definition

1cblow = cb_n_low[] > 0;

3tracks = (tr_n_hi[]>2) # ((tr_n_hi[]>1)&(tr_n_lo[]>0)) #((tr_n_hi[]>0)&(tr_n_lo[]>1)) ;

evtime = cb_time[0];

out = 1cblow & 3tracks & evtime;

End;


1/PT 1/PT

1/PT 1/PT

“Non-IsolatedTracks”

InHadronEvents

All TracksNo Trigger

- hardware

No Trigger

-missing hits

PT

Total Efficiency

200 MeV

Axial Trigger

Performance


1/PT

“IsolatedElectronTracks”

All Tracks

No Trigger

Total Efficiency

210 MeV

Stereo Trigger

Performance(with axial)

B = 1.5 T


1/PT

“IsolatedElectronTracks”

All Tracks

No Trigger

Total Efficiency

140 MeV

Stereo Trigger

Performance(with axial)

B = 1.0 T


CC Trigger Performance

.8

.6

.4

.2

1.0

Needsmorestudy


For Lots More InfoFor Lots More Info

http://www.hep.uiuc.edu/cleo/trig3/

Documents

The CLEO-c Trigger System: More Than Just Blinking Lights ! LEPP Lunch Talk Mats Selen