S254@GSI: Particle filtering in LANDzefir.if.uj.edu.pl/aladin/Presentations/land2/land2.pdfS254@GSI:...

S254@GSI: Particle filtering in LAND

J. Brzychczyk, J. Cibor, Z. Majka, P. Pawłowski, A. WielochCracow

Filtering of charged hits using VETO detectorClustering hits – a way to obtain particle numbers on

eventbyevent basis107Sn vs. 124Sn – comparison

Conclusions

Piotr Pawłowski (2005)

S254@GSI: experimental setup


S254@GSI: LAND detector


Data reduction


●Event selection ⇨Interaction trigger●Hit selection ⇨ Well Measured Hits (about 7%) :

➢ TDC1>0 & TDC2>0 & ADC1>0 & ADC2>0➢ Calibrated hit position in (110 cm ,110 cm) range.

➔We observe in LAND a large fraction (c.a. 30 %) of hits generated by charged particles.

➔In the first LAND plane this fraction achieves about 50 %.

➔The number of correlated hits is sensible for projectile isospin.

➔The charged particles can be partly identified in charge using ∆E vs. TOF map for VETO.

➔The charged particles do not disturb significantly the multiplicity vs total visible energy correlation.

Conclusions (October 2004)


Z=2 Velocity(cm/ns)

0 5 10 15 20 25 30

∆E (M

eV)

0

20

40

60

80

100

120

140

Evis vs velocity

Charge identification in VETO

Z=1

Z=2


Study of correlations between VETO and the first LAND plane

VETO LAND

0 1 2 3 4 5 6 7 8 9 10

xminx1−x0xmax

yminy1−y0ymax

tmint1−t0tmax

Hit correlation is defined by a coincidence in space and time:


62,60%


Cut 119 < ∆x < 19 (cm)19 < ∆y < 19 (cm)

1 < ∆t < 3 (ns)

Correlated hits in VETO107Sn

Uncorrelated hits:~37.4 % of total VETO hits.

62,60%5,90%


Cut 230 < ∆x < 30 (cm)30 < ∆y < 30 (cm)

2 < ∆t < 4 (ns)

Cut 119 < ∆x < 19 (cm)19 < ∆y < 19 (cm)

1 < ∆t < 3 (ns)

Correlated hits in VETO107Sn


62,60%5,90%

8,30%


Correlated hits in VETO

Cut 119 < ∆x < 19 (cm)19 < ∆y < 19 (cm)

1 < ∆t < 3 (ns)

107Sn

Cut 37 < ∆t < 4 (ns)

Cut 230 < ∆x < 30 (cm)30 < ∆y < 30 (cm)

2 < ∆t < 4 (ns)



Isolated hits in VETO

Position X (cm)180 160 140 120 100 80 60 40 20 0 20

Posi

tion

Y (c

m)

100

80

60

40

20

0

20

40

60

80

100

0

20

40

60

80

100

120Sn107

Velocity (cm/ns)0 5 10 15 20 25 30

∆E

(MeV

)

0102030405060708090

100

Sn107

Edge effect

27%

Other charged particles

18%

8% Sixth paddle defect

62,64%5,86%

8,29%

8,00%

2,37%

4,23%4,00%


Statistics for VETO hits

Edge effect

107Sn

Other charged particles

Sixth paddle defect

Dead areas between paddles

Correlated hits: ~ 77%Isolated hits: ~18%Unidentified hits: ~ 5 %

Cut 1

Cut 2

Cut 3

Recursive procedure for correlated hits identification

VETO LAND

0 1 2 3 4 5 6 7 8 9 10

xminx i−x i−1xmax

yminyi−yi−1ymax

tmint i−t i−1tmax

i=1,10

Hit correlation in two neighboring planes, i and i1, is defined by a coincidence in space and time:

For each correlated hit one searches correlations in next plane.



Charged hits in LANDCut 1

19 < ∆x < 19 (cm)19 < ∆y < 19 (cm)

1 < ∆t < 3 (ns)

Cut 2*30 < ∆x < 30 (cm)30 < ∆y < 30 (cm)

2 < ∆t < 4 (ns)

Cut 37 < ∆t < 4 (ns)

Maximum:All hits correlated with VETO

using cuts 1, 2 and 3 applied sequently.

Minimum:All hits correlated with VETO using the cut 1. Only one correlated hit per

plane is allowed.

*) Only for correlation between VETO and first LAND plane. For others we use cut 1.


Proton range in LAND

Velocity (cm/ns)10 15 20 25

Ran

ge (

plan

e nu

mbe

r)

0

1

2

3

4

5

6

7

8

9

10beam

For each hit in VETO a maximal range is calculated. No correlation is accepted out of this limit. The maximal

range for charged particles is set to 5 land planes.


Clustering hitsCorrelated hits are clustered to obtain an eventbyevent estimation

of particle number. All properties of a particle are determined by the first hit in a cluster.

VETO LAND

Neutron

Charged particleProcedure “1”

maximize number of charged particles and minimize

number of neutrons

Procedure “1” minimize number of charged

particles and maximize number of neutrons

Procedure “0”Something in between


Clustering hits procedures

16%

24%

8%

2%

30%VETO (1)*

VETO (2)*

VETO (3)*

LAND (1)*

1

LAND (3)*

20%

30%

28%VETO (1)

LAND (1)*

1

42%

10%

3%

29%

2%

28%VETO (1)

VETO (2)

VETO (3)

LAND (1)*

LAND (3)*

0

28%

SINGLE HITS*) Multiple hits per plane allowed


Comparison 107Sn vs. 124Sn

107Sn: 50 protons and 57 neutrons124Sn: 50 protons and 74 neutrons

To check correctness of our procedures we compare results from 107Sn and 124Sn

We expect similar results in both systems for:number of proton hits per eventnumber of protons per event

For neutrons we expect results scaled by neutron number ratio in both systems, at least in the vaporisation limit.


Results

Plane0 1 2 3 4 5 6 7 8 9 10

Plane0 1 2 3 4 5 6 7 8 9 10

Coun

ts/E

vent

0.20.4

0.60.8

11.21.4

1.61.8

22.2

Hit plane distribution

Sn124

Sn107

Charged

All hits

Hit plane distribution


Results

Plane0 1 2 3 4 5 6 7 8 9 10

Plane0 1 2 3 4 5 6 7 8 9 10

(Sn1

07)

σ(S

n124

)/σ

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2Sn107Sn vs. 124Comparison: Sn107Sn vs. 124Comparison:

Surprise!

50505774

Charged

Uncharged


Results

Hit charge0 1 2

Hit charge0 1 2

Coun

ts/E

vent

0

1

2

3

4

5

6

7

8

9

Hit charge distribution

Sn124

Sn107

Ratio=1.59

Hit charge distribution


Results

Particle charge0 1 2

Particle charge0 1 2

Coun

ts/E

vent

0

1

2

3

4

5

6

Particle charge distribution

Sn124

Sn107

Ratio=1.48

Particle charge distribution


Comparison with S114 experiment

Evis (MeV)0 100 200 300 400 500 600 700 800 900 1000

Evis (MeV)0 100 200 300 400 500 600 700 800 900 1000

Neu

tron

hit n

umbe

r0

5

10

15

20

25

30

Mean neutron hit number vs Evis

Sn124

Sn107

Mean neutron hit number vs Evis

We have larger energy per hit !

Erik Zude “Masse und Anregungsenergie von Projektilrestkernen im System 600 A MeV Au+Au”, Ph.D. Thesis, Frankfurt (1995).




Neutron hit number0 5 10 15 20 25 30 Neutron hit number0 5 10 15 20 25 30 M

ean

Neut

ron

num

ber

02468

101214161820

Sn124

Sn107

Mean neutron number vs hit number

We have less hits per neutron !


Neutron number0 2 4 6 8 10 12 14 16 18 20 Neutron number0 2 4 6 8 10 12 14 16 18 20 E

vis

(MeV

)0

100200300400500600700800900

1000Mean visible energy vs Neutron number

Sn124

Sn107

Mean visible energy vs neutron number


We have less energy per neutron !

~50MeV/neutron

~36MeV/neutron



Results

Particle Velocity (cm/ns)0 5 10 15 20 25 30

Particle Velocity (cm/ns)0 5 10 15 20 25 30

Coun

ts/E

vent

410

310

210

110

1

Particle velocity distribution

Sn124

Sn107Neutrons

Particle velocity distribution

Surprise!

Z=2

Z=1


Results

Velocity (cm/ns)0 5 10 15 20 25 30

Velocity (cm/ns)0 5 10 15 20 25 30

(Sn1

07)

σ(S

n124

)/σ

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2Sn107Sn vs. 124Comparison:

neutrons

protons

Sn107Sn vs. 124Comparison:

5774

5050


Results

Velocity (cm/ns)0 5 10 15 20 25 30

Velocity (cm/ns)0 5 10 15 20 25 30

Neut

rons

/Pro

tons

1

2

3

4

5

6

7

8

9

10Sn107Sn vs. 124Comparison:

Sn124

Sn107

Sn107Sn vs. 124Comparison:


Land data vs Zmax

Zmax0 10 20 30 40 50

Zmax0 10 20 30 40 50

Neut

ron

Hit N

umbe

r

4

6

8

10

12

Neutron Hit Number vs Zmax

Sn124

Sn107

Neutron Hit Number vs Zmax

Zmax0 10 20 30 40 50

Zmax0 10 20 30 40 50

Neut

ron

Num

ber

2

3

4

5

6

7

8

9

Neutron Number vs Zmax

Sn124

Sn107

Neutron Number vs Zmax

Zmax0 10 20 30 40 50

Zmax0 10 20 30 40 50

Neut

ron

Evis

50

100

150

200

250

Neutron Evis vs Zmax

Sn124

Sn107

Neutron Evis vs Zmax

Zmax0 5 10 15 20 25 30 35 40 45 500 5 10 15 20 25 30 35 40 45 50

(Sn1

07)

σ(S

n124

)/σ

0

0.5

1

1.5

2

2.5

3

3.5

4HitsClustersEvis

Sn107Sn vs 124Comparison Sn107Sn vs 124Comparison

5774

Zbound0 5 10 15 20 25 30 35 40 45 500 5 10 15 20 25 30 35 40 45 50

(Sn1

07)

σ(S

n124

)/σ

0

0.5

1

1.5

2

2.5

3

3.5

4HitsClustersEvis

Sn107Sn vs 124Comparison Sn107Sn vs 124Comparison


Land data vs Zbound

5774

Zbound0 10 20 30 40 500 10 20 30 40 50

Neut

ron

Hit N

umbe

r

0

2

4

6

8

10

12 Sn124

Sn107

Neutron Hit Number vs ZboundNeutron Hit Number vs Zbound

Zbound0 10 20 30 40 500 10 20 30 40 50

Neut

ron

Num

ber

0

1

2

3

4

5

6

7

8Sn124

Sn107

Neutron Number vs ZboundNeutron Number vs Zbound

Zbound0 10 20 30 40 500 10 20 30 40 50

Neut

ron

Evis

0

50

100

150

200

250

Neutron Evis vs Zbound

Sn124

Sn107

Neutron Evis vs Zbound


Friend tree for LAND dataGlobal variables

class LandEvent: public TAGdata{public:Int_t Nhit; // Total number of valid hitsFloat_t Evis; // Total visible energy

Int_t NeutHitMin; // Min. number of neutron hitsInt_t NeutHitAve; // Ave. number of neutron hitsInt_t NeutHitMax; // Max. number of neutron hits

Int_t NeutNumMin; // Min. number of neutronsInt_t NeutNumAve; // Ave. number of neutronsInt_t NeutNumMax; // Max. number of neutrons

Float_t NeutEvisMin; // Min. neutron visible energyFloat_t NeutEvisAve; // Ave. neutron visible energyFloat_t NeutEvisMax; // Max. neutron visible energy

TClonesArray *Hit; //> Hit table};


Friend tree for LAND dataHit variables

class LandHit: public TObject{public:Int_t ID; // Hit identifierFloat_t Time; // Hit time in [ns]Float_t X, Y, Z; // Hit position in [cm]Float_t Evis; // Hit visible energy in [MeV]UShort_t info; // Hit description};

16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 11 0 1101

Hit chargeParticlePlane number


Friend tree for LAND dataUseful global methodes

Int_t LandEvent::GetNhit(Int_t Type = 0, Int_t Charge = 0);//Returns the number of hits of charge ”Charge” //selected by the procedure “Type”

Int_t LandEvent::GetNpart(Int_t Type = 0, Int_t Charge = 0);//Returns the number of particles of charge ”Charge” //selected by the procedure “Type”

Float_t LandEvent::GetEvis(Int_t Type = 0, Int_t Charge = 0);//Returns total visible energy generated by particles //of charge “Charge” selected by the procedure “Type”

Type = 1, 0, 1Charge = 0, 1, 2


Friend tree for LAND dataUseful hit methodes

Int_t LandHit::Plane();// Returns LAND plane number for a hit; 0 for VETO

Bool_t LandHit::Particle(Int_t Type = 0); // Returns 1 if a hit is the leading hit (in procedure “Type”)

Int_t LandHit::Charge(Int_t Type = 0); // Returns hit charge attributed by procedure “Type”

TVector3 LandHit::Position(); // Returns hit position in form of TVector3;

Float_t LandHit::Theta(); // Returns hit theta angle in degrees

Float_t LandHit::Phi(); // Returns hit phi angle in degrees

Float_t LandHit::Velocity(); // Returns hit velocity in cm/ns


SummaryCharged particle hits were filtered using analysis of correlations between hits of VETO and hits detected in LAND.Three methods for hit clustering were proposed to obtain an estimation of minimum, maximum and mean neutron hit numbers in LAND. The clustering method provides also an estimation of neutron number on eventbyevent basis, as an alternative for other estimators, like total hit number or total visible energy.All three estimators give similar results when one studies cross section ratios from 107Sn and 124Sn reactions.Velocity spectrum for clustered neutrons exhibits two components. The lowvelocity component is similar to that of protons, independently of reaction.

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