Soft muon identification
description
Transcript of 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- setupCBM detector: e+e- setupECALTOF
TRD3TRD2STS
RICH
STS: track and vertex reconstruction RICH: electron identification.TRD: identification of high-energy electronsRPC-TOF: time-of-flight measurement ECAL: electron and photon identification
TRD1
CBM detector: μ+μ- setupCBM detector: μ+μ- setup
ECALTOFTRD3TRD2
STS
MUCH
TRD1
MUonCHamber system (MUCH)MUonCHamber system (MUCH)
Fe C
5 10 20 30
120 cm
STS
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
TracksTracks
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 AGeV
Yields for central Au+Au at 25 AGeV
JJ//(3095 (3095 MeV)MeV)
00
(770 (770 MeV)MeV)
(782 (782 MeV)MeV)
(1020 (1020 MeV)MeV)
++
(140 (140 MeV)MeV)
--
(140 (140 MeV)MeV)
1.95×10-5 23 38 1.28 332 368
6%4.6×10-
5 9×10-5 2.9×10-
4 — —
~1×10-6 ~1×10-3 3.4×10-
3
3.7×10-
4 332 368
multiplicity
branching ratio of channel
per event
Invariant mass spectraInvariant mass spectra
J/ψ
ρ0
ω
φ
opening angle
ptscalar product
J/ψJ/ψ > 12o > 1 [-2.4, -2.05]
ρρ, , ωω, , φφ
> 12o > 0.23 [-0.26, 0.04]
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/ψ acceptanceJ/ψ acceptance
4π sts
muchpt> 1GeV/c
1m Fe
sts: > 4 sts hitsmuch: sts + first much1m Fe: behind 1m Fe
Acceptance of RECO ρ0Acceptance of RECO ρ0
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
1 2 3 4
5 6 7 8
3000 ρ0 ➙ μ+ μ-
6%2.599
2%2.438
0.3%2.255
2%2.424
8.5%2.55
11%2.525
10.5%2.525
8%2.525
ρ0 acceptanceρ0 acceptance
4π sts
much 1m Fe
sts: > 4 sts hitsmuch: sts + first much1m Fe: behind 1m Fe
Momentum distributionMomentum distribution
much 1m Fe
Momentum Dependent Track Selection (MDTS)
Momentum Dependent Track Selection (MDTS)
MUCH detector model for MDTS study
MUCH detector model for MDTS study
μ-
π-
μ+
π+
25 Fe × 5cm p [0.5, 1.5] GeV/c
MUCH detector model for MDTS study
MUCH detector model for MDTS study
25 Fe × 5cm p [0.5, 1.5] GeV/c
Δabsorber cm
Absorber thickness vs. momentum
Absorber thickness vs. momentum
π+, π- μ+, μ-ab
sorb
er t
hic
knes
s, c
m
abso
rber
th
ickn
ess,
cm
Absorber thickness vs. momentum
Absorber thickness vs. momentum
● π+, π-
■ μ+, μ-
p = 1 GeV/cc
ou
nts
N of hits at the MUCH system: ρ0➙μ+μ-
N of hits at the MUCH system: ρ0➙μ+μ-
1111
9977
55
NMUCH hitsμ+
NM
UC
H h
itsμ
-
μ-
μ+
ρ0
34
5
2
Type of muon pairsType of muon pairs
2 hard muons
μ+
μ-
65 cm
ρ0
~ 1m Fe
p (GeV/c)
Type of muon pairsType of muon pairs
1 hard + 1 soft muons
p (GeV/c)
μ+
μ-
65 cm
ρ0
~ 1m Fe
Type of muon pairsType of muon pairs
1 hard + 1 soft-soft muons
p (GeV/c)
μ+
65 cm
ρ0
~ 1m Fe
μ-
35
Type of muon pairsType of muon pairs
2 soft muons
p (GeV/c)
μ+
μ-
65 cm
ρ0
~ 1m Fe
1hard + 1soft-soft muons
MDTS: possible pairsMDTS: possible pairs
NMUCH hitsμ+
NM
UC
H h
itsμ
-
2 hard muons
1hard + 1soft muons
2 soft muons
ρ0 acceptanceρ0 acceptance2 hard μμ 1hard + 1soft μμ
2 soft μμ1hard + 1soft-soft μμ
MDTS: possible pair combinationsMDTS: possible pair combinations
NMUCH hitsμ+
NM
UC
H h
itsμ
-
1hard + 1soft-soft muons
2 hard muons
1hard + 1soft muons
2 soft muons
MDTS: possible pair combinationsMDTS: possible pair combinations
NMUCH hitsμ+
NM
UC
H h
itsμ
-
2 hard muons
1hard + 1soft muons
2 soft muons
ρ0 acceptanceρ0 acceptance
2 hard μμ
1hard + 1soft μμ
1hard + 1soft-soft μμ
2 soft μμ
1 + 2 1 + 2 + 3
1 + 2 + 41 + 2 + 3 + 4
ReconstructionReconstruction
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 backgroundRECO 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
ω ➙ μ+ μ- : S/B ratioω ➙ μ+ μ- : S/B ratio
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
Invariant mass spectraInvariant mass spectra
minv (GeV/c2)
cou
nts
/(ev
ents
×10
GeV
/c2 )
2 hard μμ2 hard μμ
+1hard + 1soft μμ
2 hard μμ+
1hard + 1soft μμ+
2 soft μμ
■ ρ■ ω■ φ
■ ρ■ ω■ φ
■ ρ■ ω■ φ
OutlookOutlook
Tuning of momentum dependent muon
identification
Study of different absorber materials, for
example tungsten (W)
Absorber study: preliminary results
Absorber study: preliminary results
MUCH detectorbehind 5cm W
Hit density of central UrQMD event
Hit density of central UrQMD event
Fe Fe Fe FeFe
W W W WW
Fe Fe Fe FeW
W Fe Fe FeW
5cm
Thank you for your attention!Thank you for your attention!
ρ0 parameters ρ0 parameters
bg
opening angle (°) transverse momentum (GeV/c) scalar product (GeV/c)2
ρ0➙μ+μ-
ρ0
bg