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Soft muon identification. Anna Kiseleva GSI Germany, PNPI Russia. Results of the last collaboration meeting (ρ 0 , ω, φ, J/ψ) The low-mass vector meson problem (soft muons) acceptance of ρ 0 at MUCH possible solution results Absorber study: motivation Outlook.

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Soft muon identification

Soft muon identification

Anna Kiseleva

GSI Germany, PNPI Russia

  • Results of the last collaboration meeting (ρ0, ω, φ, J/ψ)

  • The low-mass vector meson problem (soft muons)

    • acceptance of ρ0 at MUCH

    • possible solution

    • results

  • Absorber study: motivation

  • Outlook


Cbm detector e e setup
CBM detector: e+e- setup

ECAL

TRD1

TOF

RICH

TRD3

TRD2

STS

STS: track and vertex reconstruction

RICH: electron identification.

TRD: identification of high-energy electrons

RPC-TOF: time-of-flight measurement

ECAL: electron and photon identification


Cbm detector setup
CBM detector: μ+μ- setup

ECAL

TOF

TRD3

TRD1

TRD2

MUCH

STS


Muonchamber system much

5 10 20 30 120 cm

STS

Fe

C

MUonCHamber system (MUCH)

  • First design study

    • absorbers:

      • 4 Fe + 1 C

      • increasing thickness

      • full thickness ~ 1m Fe

  • detectors:

    • 2 layers between absorbers

    • 1 – in front of MUCH

    • 2 – behind last absorber


Tracks
Tracks

π-

π+

1 central Au+Au event at 25 AGeV beam energy

(top view of the STS + MUCH system)


Yields for central au au at 25 a gev
Yields for central Au+Au at 25 AGeV

multiplicity

branching ratio of  channel

per event


Invariant mass spectra

J/ψ

ω

φ

ρ0

Invariant mass spectra

  • full STS tracking:

    • STS digitization

    • track finding

    • momentum reconstruction

    • primary vertex cut

  • MUCH tracking:

    • 100μm position resolution

    • STS track extrapolation

    • track finding and matching


J acceptance
J/ψ acceptance

sts

much

1m Fe

pt> 1GeV/c

sts: > 4 sts hits

much: sts + first much

1m Fe: behind 1m Fe


Acceptance of reco 0

6%

2.599

2%

2.438

2%

2.424

0.3%

2.255

10.5%

2.525

8.5%

2.55

8%

2.525

11%

2.525

Acceptance of RECO ρ0

1

2

3

4

2 hard μμ

1hard + 1soft μμ

1hard + 1soft-soft μμ

 2 soft μμ

1+2

1+2+3

1+2+3+4

1+2+4

3000 ρ0➙μ+μ-

5

6

7

8


0 acceptance
ρ0 acceptance

sts

much

1m Fe

sts: > 4 sts hits

much: sts + first much

1m Fe: behind 1m Fe




Much detector model for mdts study
MUCH detector model for MDTS study

25 Fe × 5cm

p  [0.5, 1.5] GeV/c

μ-

π-

μ+

π+


Much detector model for mdts study1

Δabsorber cm

MUCH detector model for MDTS study

25 Fe × 5cm

p  [0.5, 1.5] GeV/c


Absorber thickness vs momentum
Absorber thickness vs. momentum

π+, π- μ+, μ-

absorber thickness, cm

absorber thickness, cm


Absorber thickness vs momentum1
Absorber thickness vs. momentum

p = 1 GeV/c

counts

● π+, π-

■μ+, μ-


N of hits at the much system 0
N of hits at the MUCH system: ρ0➙μ+μ-

NMUCH hitsμ-

5

μ-

4

3

2

ρ0

μ+

5

7

NMUCH hitsμ+

9

11


Type of muon pairs
Type of muon pairs

2 hard muons

μ+

ρ0

μ-

65 cm

~ 1m Fe

p (GeV/c)


Type of muon pairs1
Type of muon pairs

1 hard + 1 soft muons

μ+

ρ0

μ-

65 cm

~ 1m Fe

p (GeV/c)


Type of muon pairs2
Type of muon pairs

1 hard + 1 soft-soft muons

μ+

ρ0

μ-

35

65 cm

~ 1m Fe

p (GeV/c)


Type of muon pairs3
Type of muon pairs

2 soft muons

μ+

ρ0

μ-

65 cm

~ 1m Fe

p (GeV/c)


Mdts possible pairs
MDTS: possible pairs

NMUCH hitsμ-

2 hard muons

1hard + 1soft muons

1hard + 1soft-soft muons

2 soft muons

NMUCH hitsμ+


0 acceptance1
ρ0 acceptance

2 hard μμ

1hard + 1soft μμ

1hard + 1soft-soft μμ

2 soft μμ


Mdts possible pair combinations
MDTS: possible pair combinations

NMUCH hitsμ-

2 hard muons

1hard + 1soft muons

1hard + 1soft-soft muons

2 soft muons

NMUCH hitsμ+


Mdts possible pair combinations1
MDTS: possible pair combinations

NMUCH hitsμ-

2 hard muons

1hard + 1soft muons

2 soft muons

NMUCH hitsμ+


0 acceptance2
ρ0 acceptance

1 + 2

1 + 2 + 3

2 hard μμ

1hard + 1soft μμ

1hard + 1soft-soft μμ

2 soft μμ

1 + 2 + 3 + 4

1 + 2 + 4


Reconstruction
Reconstruction

  • full STS tracking:

    • STS digitization

    • track finding

    • momentum reconstruction

    • primary vertex cut

  • MUCH tracking:

    • 100μm position resolution

    • STS track extrapolation

    • track finding and matching


Reco background

RECO background

2 hard μμ

1hard + 1soft μμ

1hard + 1soft-soft μμ

 2 soft μμ

1+2

1+2+3

1+2+3+4

1+2+4


S b ratio
ω➙μ+μ- : S/B ratio

S/B

2 hard μμ

1hard + 1soft μμ

1hard + 1soft-soft μμ

 2 soft μμ

1+2

1+2+3

1+2+3+4

1+2+4


Invariant mass spectra1
Invariant mass spectra

2 hard μμ

2 hard μμ

+

1hard + 1soft μμ

2 hard μμ

+

1hard + 1soft μμ

+

2 soft μμ

■ρ

■ω

■φ

■ρ

■ω

■φ

■ρ

■ω

■φ

counts/(events×10GeV/c2)

minv (GeV/c2)


Outlook
Outlook

  • Tuning of momentum dependent muon identification

  • Study of different absorber materials, for example tungsten (W)


Absorber study preliminary results
Absorber study: preliminary results

MUCH detector

behind 5cm W


Hit density of central urqmd event

Fe

Fe

Fe

Fe

Fe

W

W

W

W

W

W

Fe

Fe

Fe

Fe

W

W

Fe

Fe

Fe

Hit density of central UrQMD event

5cm


Thank you for your attention
Thank you for your attention!


0 parameters
ρ0 parameters

opening angle (°) transverse momentum (GeV/c) scalar product (GeV/c)2

ρ0

bg

bg

ρ0➙μ+μ-


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