View
218
Download
0
Embed Size (px)
Citation preview
Study of -production reaction π–p → ηn
in the near-threshold region
Experiment object:
Precision data on –pηn reaction DCS measurement
Contents:
1. Experiment and setup2. Neutral meson spectrometer characteristics
3. Experimental data processing4. Experimental results and conclusion
Dr.Bayadilov D., Meson Physics Laboratory, PNPI
1. PNPI synchrocyclotron -channel (Gatchina, Russia)
1. ΔP/P=1,5% (FWHM)2. δP/P=±0,5%
2. Experimental setup at PNPI synchrocyclotron -channel (Gatchina, Russia)
3. Experimental setup scheme
4. Experimental setup
5. Neutral meson spectrometer cell
• Individual crystal size 6060300 mm3 (16Xo)• Photomultiplier type – FEU-97 ( 55 mm)• PM supply – special high voltage multiplier• Dynode signals are used in trigger logic
6. Individual crystal energy calibration
a) Cosmic rays; b) Electrons
7. Neutral meson spectrometer characteristics
Energy: M 6%
Angle: 1m 1
Time: 10 nsec
8. Trigger
D1 and D2 – the sum of dynode signals from central parts of each calorimeters
9. E2 vs. E1
distribution for – momentum 720 MeV/с
10. Monte Carlo simulation. E2 vs. E1distribution for – momentum 720 MeV/с
11. DCS calculation
,cos2 ..
..
mcp
mc
BrNAN
N
d
d
Nη – number of produced and registrated η-mesons
at solid angle 2cosc.m. (cosc.m.=0.2), N- – number of ––mesons drop on target
А – setup acceptance, Br – branching ratio of decay
Np –number of hydrogen nucleus per cm2 of the target
12. η-mesons counts and acceptance
13. DCS of –pηn reaction in C.M.(preliminary)
14. Data fit with Legendre polynomial expansion
)(cos)(cos ..22
..110
..mcmc
mc
PaPaad
d
15. ai coefficient ratios
1) Neutral meson spectrometer was designed and created in PNPI, it has good angle and energy resolution
2) Measurements of DCS of –pηn reaction were made with high precision at three momenta 700 , 710 , 720 MeV/c
3) It is shown that at 700 MeV/c the DCS angular dependence is isotropic, indicating the S-wave character of the -production process
4) At higher momenta a significant D-wave contribution has led to the anisotropic angular dependence resulting in bowl-like shape
5) Further improve our data with kinematical fit6) Combined analysis of η photoproduction and π-production on
protons will improve determination of coupling constants of D13(1520) and S11(1535) resonances
7) Adding our results to the world database and providing a new PWA solution
Conclusion and outlook
Kinematic fit