Hadron performance in bes iii detector
Download
1 / 32

Hadron Performance in BES III detector - PowerPoint PPT Presentation


  • 75 Views
  • Uploaded on

Hadron Performance in BES III detector. Ji X.B., Li G., Sun S.S., Wang L.L. IHEP Jan. 10 – 12, 2006. Outline. Reconstruction efficiency of hadron PID & its efficiency J/  physics ( ) Summary. All works are based on BOSS 5.0.0. Reconstruction efficiency.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Hadron Performance in BES III detector' - haile


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Hadron performance in bes iii detector

Hadron Performance in BES III detector

Ji X.B., Li G., Sun S.S., Wang L.L.

IHEP

Jan. 10 – 12, 2006


Outline
Outline

  • Reconstruction efficiency of hadron

  • PID & its efficiency

  • J/ physics ( )

  • Summary

All works are based on BOSS 5.0.0

BES III meeting


Reconstruction efficiency
Reconstruction efficiency

  • is used to get the efficiency of proton, anti-proton and pion

  • is used to get the efficiency of pion and kaon and KS

  • is used to measure the soft pion efficiency

BES III meeting


Method
Method

  • Good hardron selection(Very loose cut criteria )

    Rxy < 1 cm, Z < 5 cm|cos\theta| < 0.93probPID > 0.001 (combined probability of dE/dx, TOF1, TOF2)

  • Event Selection At lease 3 particles should be reconstructed and identified

  • Efficiency

BES III meeting


Advantage:

  • Large Branch ratio (6.0  0.5)x 10-3

  • No neutral tracks

  • Momentum range is wide

  • Low background

    Total 50,000 MC events are used.

BES III meeting


Momentum distribution
Momentum distribution

pi

P

(0.0, 0.8)

Range: (0.0, 1.1)

BES III meeting


Missing mass
Missing mass

P

AP

-

+

BES III meeting


Match criteria
Match criteria

  • The missing direction |cos < 0.8|

  • The angle between the expected direction and the measured direction  < 15o

cos

BES III meeting


Distribution
 distribution

AP

P

+

-

BES III meeting


Reconstruction efficiency

P

AP

-

+

BES III meeting


Sun s s
(Sun S.S.)

  • 100,000 MC sample is used

  • is used to get the efficiency of pion and kaon

  • is used to get the efficiency of KS

BES III meeting


Missing mass1
Missing mass

mK2

m2

BES III meeting


Reconstruction efficiency

+

-

K+

K-

BES III meeting


Reconstruction efficiency of KS

mKs2

BES III meeting


(Li G.)

  • The decay mode of J/+- is used to reconstruct the J/ 

  • The particle with momentum less than 0.5 GeV/c is regarded as pion

BES III meeting



Charged particle identification
Charged Particle Identification

  • Method:

     of dE/dx, Tof after reconstruction should obey standard normal distribution for a certain charged track:

    χdEdx=((dEdx)measured -(dEdx)exp)/(dEdx)exp

    χTof=((TOF)measured -(TOF)exp)/(TOF)exp

    So χ2= χ2dEdx+χ2TOF1+χ2TOF2

    (+χ2EMCE+χ2TOF1Q+……)

    should obey χ2distribution.

    We use quantity CL(χ2measured→+∞) of χ2distribution to identify charged particles.

BES III meeting


Charged particle identification1
Charged Particle Identification

  • Distribution of CL ( sample)

BES III meeting


Rec pid efficiency
Rec & PID efficiency( )

Prob>0.001

P

AP

-

+

BES III meeting


Rec pid efficiency1
Rec &PID efficiency( )

rec. only

rec. & PID

K-

K+

Prob>0.001

-

+

BES III meeting


Mc study of

J/ygpp

M=1859 MeV/c2

G < 30 MeV/c2 (90% CL)

0.2

0

0.1

0.3

M(pp)-2mp (GeV)

MC Study of .

  • Motivation

    • “Observation of a near-threshold enhancement in the ppbar mass spectrum from radiative J/ppbar decays” BES II, 2003

    • JPC maybe 0-+ or 0++

    • High precision measurement is important to determine the properties of the structure

BES III meeting


Mc study of1
MC Study of .

(Only very preliminary results)

  • The mainly background is

  • MC used(all generated by HOWL) :

BES III meeting


Event selection
Event Selection

  • Two good charged tracks with opposite charge

  • At least one good photon

  • Umiss < 0.02, Ptr < 0.001Umiss = Emiss – PmissPtr = 4Pmiss2sin2(/2)

BES III meeting


Umiss

Ptr

signal

background

BES III meeting


J/X

BES III meeting


Summary
Summary

  • The tracking efficiency and PID efficiency of hardrons are measured from different decay modes

  • A rough estimation of proton anti-proton threshold enhancement

  • Many works should be done in the future

BES III meeting


Thank You!

BES III meeting


Rec and pid
Rec and PID

BES III meeting


1M

BES III meeting


Different pid
Different pid

BES III meeting


Chi

BES III meeting


Angle
angle

BES III meeting


ad