Mozaic trigger system for transverse momentum physics

G.Vesztergombi, A.Agocs, B.Bozsogi, A.Fulop

CBM Collaboration Meeting

GSI – Dubna13-18 Oct, 2008

Motivation for new measurements below = 20 GeVs

Practically no high or medium Pt data between Einc = 24 and 200 GeV

Mysterious transition around 80-90 GeV: convex versus concave spectra

Energy threshold for Jet-quenching?

Emergence of Cronin-effect in pA interactions is completely unknown

energy dependencecentrality dependenceparticle type dependenceparticle correlations

Production of Upsilon (9.5 GeV) particles near the threshold.

NA49 (CERN) results at 158FODS (IHEP) at 70 GeV

Beier (1978)

Y production

Due to high mass ( 9.5 GeV/c2) two high pT particle in leptonic decay:

pT > 3 GeV/c

High selectivity for high pT pair even without PID

Benchmark NA49 pp at E = 158 GeV 30 events/spill Events Energy > 3 GeV/c > 4 GeV/c > 5 GeV/c

2 106 158 100 1 0.01Estimates with the assumption 1011 proton/sec 109 interaction/sec

1 day=1014 158 5 109 5 107 5 105

Suppression 10-1 10-2 10-3

1 day=1014 90 5 108 5 105 500

20 day=2 1015 90 1010 107 104

20 day=2 1015 45 107 10 0

Suppression 10-3 10-6 10-10

For symmetric nuclei max energy 90/2 assumed

CBM Perspectives

Special requirements for Y-> e+e- and high pT

Extremely high intensity - Pile-up

Segmented multi-target - Relaxed vertex precision

Straight tracks - High momentum tracks

DREAM: 109 interactions/sec

High transverse momentum means high 3-momentum

Illustration for mid-rapidity at sqrt(s) 7 and 14 GeV

( )ELab

( )( ) =plong

ptrans 0 0 1

0

0

22Tpm

0

longp >= 0Lab

E >= 22Tpm

ptrans

Beam ptrans Lab

E

25 55525 2 5

5 22

z [cm]

x,y

[cm

]

Px=Py = 1 GeV/c; Pz= 5 GeV/c

Px=Py= 3 GeV/c Pz = 10 GeV/c

High ( > 5 GeV/c ) momentum Straight track

“Straight” tracks from main vertex

1-dim Hough – transform:- histogram

N(i) in bins

M(i) = N(i) + N(i+1 ) in 2bins

Correct for bin boundary crossing:

Tracks with pxz > pmin remains within the pminwedge

SELECTION on pxz

i

i+1

j

j+1

3 dimensional scheme

k=1

k=2

k=3

Mosaic cells in plane “k” : M(i,j,k)

(i,j) Corridor contains: M(i,j,k), M(i,j+1,k), M(i+1,j,k), M(i+1,j+1,k) k=1,2,3

MAPS vs Hybrid

Vertex resolution: dz = 1 mm, dx,dy= 0.05 mm

High intensity: radiation hard

Practical 4+ 2 + 3 = 9 planes ( 4 Hybrids + 5 strips)

Selectivity depends on the availability of TOF information

s = sqrt(XX*XX+YY*YY) - delta

delta

Sagitta:

10-20 cm track sections are practically straight fractals

(XX,YY,ZZ)

4 hybrids 2 + 3 strips

2 4 6Basic planes

* * **

** **

*

Silicon planes

Basic planes: #2 = (x2,y2,z2) pixel , #4 = (x4,y4,z4) pixel, #6 = (x6,z6) strip

Parallel processing: CORRIDOR # corNum

Straight tracking in #2 and #4 planes in space => (mx,bx) and (my,by) Approximation: starting direction is given by (mx,my)

Separate track matching in xand y for planes 5-9

Matching in #1 and #3 pixel planes in space

TUBE definition:

x-tube: xi = mx*(zi-z2) +bx +parabol(x6,z6,zi) +/- deltaxiy-tube: yi = my*(zi-z2) +by +/- deltayi

New algorithm

4-5 GeV/c

pT > 1.0

7-8 GeV/c

pT > 1.0

9-10 GeV/c

pT > 1.0

15-17 GeV/c

pT > 2.5

20-40 GeV/c

pT > 2.5

Acceptance

Npoint=9

+ -

pxz

pT

Selecting only tracks with pT>2.5 GeV/c

Npoint=9

PileupFixed pT-cut at 1.8GeV/c

No pileup : Tracks with ptin > 1.8: 1136 ptin < 1.8 but ptrec > 1.8: 430

Npileup = 10 : Tracks with ptin > 1.8: 1136 FAKE and ptrec error : 1 + 430

Npileup = 100 : Tracks with ptin > 1.8: 1136 FAKE and ptrec error : 28 + 430

Npileup = 1000 : Tracks with ptin > 1.8: 1136 FAKE and ptrec error : 464 + 430

No LOSS of GOOD tracks due to pileup (exhaustive search!!!)

Number of FAKE triggers even in 1000-fold pileup is < 50 %

Pileup cont.

pT dependence: No pileup 1000-fold pileup

1.8 GeV/c 430/1136 464+430/1136

2.0 GeV/c 312/704 363+312/704

2.2 GeV/c 208/453 306+208/453

2.4 GeV/c 151/301 265+151/301

2.6 GeV/c 103/213 205+103/213

3.0 GeV/c 52/154 168+ 52/154

The FAKE/GOOD ratio is moderately increasing with pT

Deviations within the tubedx Charge*dx

Y-deviations

Difference between exact direction and mx

pT > 1.0 GeV/c pT > 2.5 GeV/cpxz

DAQ scheme

Mozaic DAQ systemTwo separate systems:

PRETRACKING network: Pixel [#2 , #4] + Strip [#6x]

TRACK-QUALITY TUBE network:Pixel [ #1, #3] + Strip[#5x, #5y, #6y, #7x, #7y, #8x, #8y, #9x, #9y]

In each network parallel CORRIDOR processors: CorID =corNUMNumber of CORRIDOR processors: ndx*ndy

Data select their routes according to plane number and corNUM

In plane „zi” track-hit „xi,yi” calculates its corridor address:

corNum = idx*ndy + idy

Corridor processors

OLD system: consecutive cycling on all „planes”

If only 2 points per plane: number of cycles = 2(4+2*5) = 214 = 16384

NEW system: cycling only on 3 „planes” (for pixels x and y has common cycle)

If only 2 points per plane: number of cycles = 2(2+1) = 23 = 8

The PRETRACKING is producing a list containing:

corNUM, x1,x3,x5,x7,x8,x9, y1,y3,y5,y6,y7,y8,y9

There is NO PROCESSING TIME in the TRACK-QUALITY TUBE network becauseIt is only an ASSOCIATIVE memory which provides YES/NO.

The gain in processing time (if only 2 points per plane): 211 = 2048-fold

Mozaic trigger for low pT

Silicon tracker in FAIR-CBM experiment

Special trigger for high intensity 1O9 interaction/sec in pp,pA reactions

SIMULATION: 4 hybrid(pixel) + 5 strip = 9 silicon planes

“Mosaic” front-end structure (dx,dy) regions in M(i,j,k) buffers.

Exhaustive search for all tracks in (pmin,pmax) corridors.

TEST RESULT: 1000-fold PILEUP in pC interactions

Corridor-width optimized for tracks pT > 3 GeV/c

Algorithm efficiency: 100 %, with some multiple solutions picking up some random points, giving practically the same track-parameters

Highly parallel algorithm is well adapted for processor clusters.

Can be adapted for AA to reconstruct ALL particles with low pT corridors

END

For discussion:

Physical mosaic cells can be different from logical cells.

Hybrid (pixel) : logical cells may be created by softwareStrip planes: hardware should be harmonized

Corridors can be filled by hardware or software

Number of processor can be less than number of corridors

Corridor’s processing speed can be very fast if they are narrow

Corridors can be arranged hierarchically for processing order

0 0 0 1 0 0 0 0 1 0 0 1 0 0 1 0 0 2 0 00 3 22 5 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 04 0 48 73 44 7 1 0 0 0 1 1 0 0 0 0 1 0 0 00 0 34 81 90 81 35 0 0 0 0 0 0 0 1 0 1 0 0 00 2 28 83 92 87 89 81 25 0 1 0 2 0 1 0 0 0 1 00 0 17 69 93 89 91 86 87 78 16 1 1 0 0 1 0 0 0 00 0 4 40 86 90 90 85 91 87 86 63 13 1 0 1 0 0 1 10 1 1 18 72 94 91 90 89 85 87 87 83 42 9 0 1 0 1 00 0 0 9 52 88 90 88 85 86 93 93 91 89 77 50 8 0 0 30 0 1 0 28 72 88 90 90 91 85 90 86 91 90 84 80 37 0 00 0 0 0 8 51 74 92 92 87 91 86 91 95 90 83 93 88 75 260 0 0 1 1 37 62 89 87 87 88 84 85 92 96 92 91 90 90 89

Plong [GeV/c]

Ptrans [G

eV/c]

10 20 30 40 50

7+2 Points efficiency

2

0

4

6