D. Elia, INFN Bari ALICE Offline Week - June 2004 1

Recent results Recent results from SPD beam from SPD beam

testtest

D. Elia, R. SantoroINFN Bari

ALICE Collaboration - SPD Group

D. Elia, INFN Bari ALICE Offline Week - June 2004 2

SPD beam test in 2003 (I)

Table

MWPCQuartz Scintillators

Mini bus 0

Pb-Target

Table: 150 cm

beamMini bus 1

Middle plane

Half stave

158 A GeV/c In beam (104 ions/spill, 15 days)

4 mm thick Pb target

3 days with 120 GeV/c proton/pion beam

D. Elia, INFN Bari ALICE Offline Week - June 2004 3

Target: 4 mm Pb Trigger: quartz counter (beam) + 2 cm x 2 cm scintillator (interactions) Mini bus 0, 1: 2 single chips/mini bus mounted in crossed way Middle plane: single chip under study Half-stave: read out through MCM including optical module

2.8 GB of data collected

Half-stave

TargetMini bus 0

Mini bus 1

Middle plane

SPD beam test in 2003 (II)

D. Elia, INFN Bari ALICE Offline Week - June 2004 4

SPD beam test in 2003 (III)

Used for this analysis: proton/pion beam data (detailed understanding of detector behaviour)

D. Elia, INFN Bari ALICE Offline Week - June 2004 5

SPD beam test in 2003 (III)

Minibus 0

Minibus 1

Test chip

Main studies:- alignments, residuals and resolution- cluster analysis- detection efficiency

425 m

50 m

256 rows

32 columns

D. Elia, INFN Bari ALICE Offline Week - June 2004 6

SPD beam test in 2003 (III)

Minibus 0

Minibus 1

Test chip

Available samples:- focussed and wide beam data- full scan of threshold settings- tilt angle scan (inclined tracks)

D. Elia, INFN Bari ALICE Offline Week - June 2004 7

Alignments

Fine tuning of the alignment for the test plane:- track prediction residuals centering

Alignment of the minibuses and track reconstruction

rms(x) = 117 m(y) = 14.9 m

All cluster tupes:

D. Elia, INFN Bari ALICE Offline Week - June 2004 8

Residuals and resolution (I)

Single pixel-clusters:

rms(x) = 121 m(y) = 14.9 m

(x) = 12.6 m(y) = 13.6 m

Double-pixel clusters:

D. Elia, INFN Bari ALICE Offline Week - June 2004 9

Residuals and resolution (II)

Residuals for singlepixel clusters:

rms(x) = 121 m(y) = 14.9 m

Spatial precision of the telescope (simulation): telescope 10 m

pixel(x) = 121 m pixel(y) = 11 m

@ VTH = 200

D. Elia, INFN Bari ALICE Offline Week - June 2004 10

Impacts vs cluster size

Single-pixel cluster

Double-x-pixel cluster

Double-y-pixel cluster

D. Elia, INFN Bari ALICE Offline Week - June 2004 11

X-impacts vs cluster size

Single-pixel cluster

@ VTH = 200

Double-x-pixel cluster

D. Elia, INFN Bari ALICE Offline Week - June 2004 12

X-impacts vs cluster size

@ VTH = 200

= 15 m

D. Elia, INFN Bari ALICE Offline Week - June 2004 13

Y-impacts vs cluster size

Single-pixel cluster

Double-y-pixel cluster

D. Elia, INFN Bari ALICE Offline Week - June 2004 14

Residuals vs threshold (I)

@ VTH=80

(y) = 16.6 m

@ VTH=120

(y) = 17.9 m

@ VTH=200

(y) = 14.9 m

@ VTH=214

(y) = 13.8 m

Single-pixel clusters

D. Elia, INFN Bari ALICE Offline Week - June 2004 15

Residuals vs threshold (II)

Double-y-pixel clusters

@ VTH=80

(y) = 21.0 m

@ VTH=120

(y) = 14.1 m

@ VTH=200

(y) = 13.6 m

@ VTH=214

(y) = 15.8 m

D. Elia, INFN Bari ALICE Offline Week - June 2004 16

Cluster type studies (I)

1 32 4 5

7

6

9 108

12

11

13

Following classification implemented:

14 = all other types

D. Elia, INFN Bari ALICE Offline Week - June 2004 17

Cluster type studies (II)

1 32 4 57

8

VTH = 200

D. Elia, INFN Bari ALICE Offline Week - June 2004 18

Cluster type studies (III)

1 32 4 57

8

910

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Cluster type studies (III)

6 11

12

13

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Cluster type studies (IV)

VTH=214

VTH=200

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Cluster type studies (V)

1 32 4 57

8

VTH = 214

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Cluster type studies (VI)

VTH=200

VTH=180

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Cluster type studies (VII)

VTH=140

VTH=120

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Cluster size vs threshold (I)

@ VTH=214 @ VTH=200 @ VTH=160 @ VTH=90

D. Elia, INFN Bari ALICE Offline Week - June 2004 25

Cluster size vs threshold (II)

D. Elia, INFN Bari ALICE Offline Week - June 2004 26

Efficiency study Event selection:

- 1 cluster on each of the tracking planes

- track crossing the test plane (acceptance limits)

@ VTH>150:

- efficiency 99.9%

Threshold scan study: