motivation; cbm experimental setup, mvd+sts; open charm at sis 100; he cooling (no beam pipe)

• Motivation;

• CBM experimental setup, MVD+STS;

•Open charm at SIS 100;

•He cooling (no Beam Pipe)

• Open charm at SIS 300

• D0K-+, D+K-+ +, Ds+ K+K-+;

and +c pK-+

• Open charm trigger;

• {Ξ0Λ}b detectability study

• Summary

D0, D+, Ds+ , c , D*

I.Vassiliev, Open charm physics at CBM

sts

K-

+

MVD +

MAPS

D+

21.04.23 1CBM Split

21.04.23 CBM Split 2

Charm production at threshold energies (motivation)

Input to hadronic transport models

(HSD):

Parameterization of measured cross

sections

O. Linnyk et al., Nucl. Phys. A786

(2007) 183No data: (why?)X-sections,flow(s),pt, y;D0/D+, D0/Ds, D0/c ratios

• 10 stations (5, 10,30,35,40,50,60,75, 95,100 cm) 2 first in vacuum

MAPS: 300 and 500 (m),

with 10x10 m cell size

• Strip-detectors (400 m),

60 m strip-pitch,

1cm (min.) strip length;

• Realistic hit producers;

• -electrons in, no pile-up and

clusters for the MAPS detectors

MVD

100K p+C

21.04.23 3CBM Split

21.04.23 CBM Split 405.10.09 4

11h 44h

21.04.23 CBM Split 505.10.09 5

Fast SIMDized CA tracking in STS racking in STS by I.Kisel

1.125s eff = 97.9%

p+C 30GeV

MC RECO

XZ Top View

RefPrim efficiency : 0.999 RefSec efficiency : 0.895 Refset efficiency : 0.991 Allset efficiency : 0.932Clone probability : 0.023

21.04.23 CBM Split 605.10.09 6

p+C 30GeV

MC RECO

Fast SIMDized CA tracking in STS racking in STS

XY Rear View

e+

e-

p

p

K-

-

+

21.04.23 CBM Split 705.10.09 7

p+C 30GeV

Fast SIMDized CA tracking in STS racking in STS

50 pile-up

21.04.23 CBM Split 805.10.09 8

Invariant mass resolution

21.04.23 CBM Split 905.10.09 I.Vassiliev, Dubna, May-09 9

Z vertex resolution

21.04.23 CBM Split 1005.10.09 10

primary vertex reconstruction

pC background control

4.5 tracks central, 1 track mbias

K-

+

+

2geo

D+

21.04.23 CBM Split 11

21.04.23 CBM Split 1205.10.09 12

Open charm z-vertex reconstruction

v221

5 cm 10 cm

21.04.23 CBM Split 1305.10.09 13

Invariant mass spectra

3 cut 4 cut

HERA-B p+A 920GeV2weeks @ 1.5MHzparticles ID by RICH

MD+ HSD=2.710-8

BR = 0.095

with PV BG suppressed 10-30 times!

eff = 13.2 % eff = 11.6 %

21.04.23 CBM Split 14

Simulation studies with He, no beam pipe (AuHe minbias)

HeHe

21.04.23 CBM Split 15

Acc

(%)

Simulation studies with He, no beam pipe (AuHe minbias)E

ffic

ien

cy (

%)

21.04.23 CBM Split 16

Acc

(%)Simulation studies with He,

no beam pipe (AuHe minbias)

A. Kotynia

S/BG ~0.15 and rapidly decreasing with Z

21.04.23 CBM Split 17

698 tracks 509 tracks

1.125s 0.077seff = 97.9% eff = 95.3%

698 reco tracks

771 mc track 534 mc track

RefPrim efficiency : 0.979 (0.93)

0.88 RefSec efficiency : 0.833 Refset efficiency : 0.961 Allset efficiency : 0.905Clone probability : 0.032Ghost probability : 0.044

primary vertex reconstruction

pvsv K-

5.5 µm

-

+

UrQMD background control

21.04.23 18CBM Split

secondary vertex reconstructionD0 z-vertex resolution vs second MAPS z-position

pvsv K-

5.5 µm

-

+

real

istic

500 m

3-d MAPS

21.04.23 19CBM Split

Open charm z-vertex reconstruction realistic MAPS

D0K-+

21.04.23 20CBM Split

21.04.23 CBM Split 21

Strategy: background suppression keeping maximum of efficiency

single track parameters based cuts: χ2

prim on the impact parameter value 6.5-7.5 !

IP impact parameter cut (upper value) 1mm track momentum cut p > 1.0 GeV/c track transverse momentum pt > (0.2-0.5) GeV/c

multiple track (particle) parameters based cuts: χ2

GEO geometrical constrained fit 3.0 χ2

TOPO topological constrained fit 2.0 signal particle primary vertex DCA < 30 m

21.04.23 CBM Split 22

D0 and D0 @ 25AGeV minv spectra

1010 events

21.04.23 CBM Split 23

D+ and D- @ 25AGeV minv spectra

21.04.23 CBM Split 24

Ds+ @ 25AGeV minv spectra

K+K-+ (5.3 ± 0.8)%

+(4.5 ± 0.4)%-> K+K-(2.2 ± 0.2)%

K+K*(892), K*(892) ->K-+(2.5)%

21.04.23 CBM Split 25

Ds+ @ 25AGeV minv spectra

Open Charm Trigger-algorithm

CbmL1TrackFinder

CbmL1TrackFitter

Charm Track Candidates Selection χ2prim > 3

Charm Pairs χ22geo

< 3.0, zv <1 cm χ2

topo < 3.0, minv > 1.3 GeV

Charm Triplets χ23geo+topo < 3.0 ☺

D+c Ds

☺D0☻☻

RFmb = 125RFcen = 14

21.04.23 26CBM Split

21.04.23 CBM Split 27

Detached Vertex Trigger: first results

D0+D0 D++D- Ds+ c

+

decay channel K-+ K-+ + K-K+ + p K-+

MHSD1.5·10-4 4.2·10-5 5.4·10-6

MSM8.2·10-4 8.4·10-5 1.4·10-4 4.9·10-4

BR(%) 3.8 9.5 5.3 5.0

geo. acc.(%) 39.9 45.5 32.8 55.5

s.t. rec. eff. 98 97.5 97.5 97.6

z-resolution (m) 47 47 60 58

total eff. (%) 4.4 2.6 1.0 0.2

m (MeV/c2) 10 10 10 10

S/B2 2.1/6.4 1.1/2.4 5.0 0.6

yield(K/1012cen) 56+174 103+195 2.9HSD 75SM51

Open charm properties table (25AGeV)

21.04.23 28CBM Split

{Ξ0Λ}b -dibaryon detectability study in the CBM experiment

{Ξ0Λ}b→ΛΛ→ pπ-pπ-

{Ξ0Λ}b

Λ

Λ

p

p

π-

π-

π-

π-p

p

{Ξ0Λ}b

Λ

Λ

STS

MAPS

Event topology:

π-

π-

π-

p

p

p

Λ2

Λ1

Λprim

{Ξ0Λ}b

χ2topo

χ2topo

pv

{Ξ0Λ}b -dibaryon signal and ΛΛ-background z vertex distribution

We use all cuts except cut on z vertex

Distribution was fitted with exponent

Integral under exponent from 3 to

was calculated.

To estimate amount of ΛΛ candidates

for 1012 events integral was multiplied

by 108

Reconstructed invariant mass distribution with theoretically predicted parameters

50K

50K

Reconstructed invariant mass detectability level (multiplicity few10-6)

M = 7·10-650

Summary

CBM detector is suitable for the Open charm measuring at SIS 100 and SIS 300 energiesHe inside MVD and STS isn’t good for the Open charm New Primary vertex finder has been developedNew KFParticleCBM detector can collect about 50K {Ξ0Λ}b -dibaryons per 1012 central collisions Au+Au 25 AGeVDetectability limit is about few·10-6 H-dibaryons per central event Plans:-electrons, pile-up, clustering in the MAPS, new detector geometries and passive materials;

21.04.23 34CBM Split