1. BGOeggと前方PWO検出器を用いたメソン光生成の研究
宮部　学
東北大学・電子光理学研究センター
ELPH研究会C015
2016/12/01

2. Physics Motivation h’ mesic nuclei Other meson production
h’ and UA(1) anomaly
Yuji Matsumura, ELPH workshop C015(12/02), 「LEPS2/BGOegg 実験における原子核中で の η' メソンの性質変化測定」
Other meson production
f1(1285) /h(1295), f2(1270)
Property, Reaction mechanism.

3. h’(958) and UA(1) anomaly
The experimental mass of h’ is more than 2 times larger expected value.
UA(1) anomaly effect.
Origin of large h’ mass
Chiral symmetry breaking
UA(1) anomaly
Daisuke Jido, Hideko Nagahiro, and Satoru Hirenzaki,
Phys. Rev. C 85 (2012) (R).
No experimental information for UA(1) anomaly effect

4. h’-mesic nuclei Search for the h’ mesic nuclei using nuclear target.
Strong attractive force and small absorption
Attractive force
UA(1) anomaly effect
Absorption
ReW0～ MeV（CB- ELSA）
M. Nanova et al., PLB 710, 600 (2012)
Experimental results
Re ah’N<0.8fm
Phys. Lett. B474(2000)p416
|ah’N| <0.1fm　
Phys. Lett. B482(2000)p356
Optical potential with Chiral unitary model
ReV >> ImV　(possible)
　→ more detailed experiment!
Transparency ratio
Search for the h’ mesic nuclei
using nuclear target.

5. h’ mesic nuclei in (g,p) reaction
Low recoil momentum of h’
Experimental parameters
Eg 1.6~2.9 GeV
Target C
Forward proton detection
C( g, p )X　missing mass
2011

6. Lineshape analysis
Eur. Phys. J. A (2013) 49: 132
ω lineshapes for the different nuclei are compared and a broadening of the ω signal for the niobium target is observed in comparison to the liquid- hydrogen target.
h’ linesapes study
Lineshape comparison for the three targets LH2 (dashed green), C (dotted red) and Nb (black)

7. Other meson production

8. f1(1285)/h(1295) photoproduction
f1(1285)/h(1295) decay into p p h.
h(1295)
first radial exictation of h?
h(1405), h(1475)
Glueball? Gluon component?
PHYSICAL REVIEW C 93, (2016)

9. Vector meson photoproduction
Eur. Phys. J C26, 271 (2002)
Vector Meson Dominance
Meson Exchange
Dominant at low energies
Pomeron Exchange
Slowly increasing with energy.  N
 

 (~ss) N
uud

10. Recent Result from LEPS
T. Mibe, et al. PRL (2005) E1 E1 E2
ρ3=0.199+/-0.052 E2
ρ3=0.189+/-0.030
Bump structure around 2GeV.
Natural parity exchange is dominant
　→　0+ glueball ?
Pseudo scalar meson exchange is not negligible.
CF. Hiraiwa-san’s previous talk

11. Glueball, Pomeron/Odderon
The phenomenological pomeron has long been established as an effective Regge pole with
Trajectory.
Phenomenological odderon, a C = P = −1
partner of the C = P = +1 pomeron, should not exist.
Commun. Theor. Phys. (Beijing, China) 49 (2008) pp. 729–738

12. f2(1270) photo-production Rho, Omega, gamma and Odderon exchange
careful analysis of all contributing C = +1 and C = -1 exchanges is necessary
arXiv: v3 [nucl-th] 20 Nov 2015

13. Physics Motivations h’ mesic nuclei Other meson production
h’ and UA(1) anomaly
Yuji Matsumura, ELPH workshop C015(12/02), 「LEPS2/BGOegg 実験における原子核中での η' メ ソンの性質変化測定」
Other meson production
a2, f1(1285) / h(1295), f2(1270)
h production
T. Nam, JPS meeting 2017A, “Eta photo-production from proton target at LEPS2/BGOegg experiment (1)”
Toshikazu Hashimoto, JPS meetin 2017A, "LEPS2/BGOegg 実験における液体水素標的を用いたη 中間子光生成反応(2) “
h’ production from nucleon
h’ scattering length

14. Experiment

15. LEP2 Project at SPring-8 Laser room
Backward Compton Scattering
High intensity：
Multi (ex. 4) laser injection
w/ large aperture beam-line
& Laser beam shaping
　 ~ 5 x 10 6 photons/s
（LEPS ~10 6 ）
Recoil electron
(tagging)
LEP
(GeV g -ray)
Laser room
Inside SR bldg
30m long line
8 GeV electron
Laser
Outside SR bldg
Experimental bldg
Beam dump
BGOegg
LEPS2
spectrometer
Storage ring
Energy spectrum with
large BGO crystal (f 8 cm x L 30cm )
Large acceptance EM calorimeter BGOegg + PWO

16. Large acceptance EM calorimeter BGOegg
Egg like shape
Total volume 264L
Total weight 1.9t (crystal only)
Two type photomultipliers
H11334 (metal package type)
H6524 (head on type)
Very few dead-region
Without housing material
Only with 3M-Vikuity ESR film reflector.

17. Overview of BGOEGG Forward (24°-90°) Backward (90°-144°)
13 layers (153L)
Backward (90°-144°)
9 layers (112L)
1320 BGO Crystal with 220mm(20X0) length
Each crystal is pyramidal shape with isosceles trapezoid face.
60 BGO crystals per layer
Cross section view of BGOEGG

18. Construction of BGOegg
Assembly in ELPH ~ 2012/12
Departure from ELPH ~ 2012/12/13
Arrival in LEPS2 ~ 2012/12/15
Beam Ready 2013/12~

19. PWO forward gamma counter (FG)
Total 252 PbWO4 crystals
PWO crystal
22 x 22 x 180 mm
r = 8.3 g/cm3
X0 = 0.89 cm
RM = 2.0 cm
From particle data group
Fast light output
Maintenance and performance test in ELPH
ELPH 2016
LEPS 2003

20. Previous setup Time of flight counter Charge identification detector
Resistive Plate Chamber (RPC)
Charge identification detector
Inner Plastic Scintilators(IPS)
Caharged particle tracker chambers
CDC, DC
BGOEGG
+ Charge ID
+ CDC
E949 Solenoid
RPC DC
~12m g
IPS
CDC
RPC DC FG

21. New setup candidate BGOegg covers from 24 – 144 degree
IPS and CDC for charge identification
FG (PWO) covers degree
New charge veto counter for PWO
BGOegg upgrade
(XX-24 degree in future)

22. Performance of BGOegg 3.1 mm for centeral modules
3.7 mm for peripheral modules
@1GeV
1.4% energy 1GeV
T. Ishikawa, Nucl. Instr. Meth. A837(2016)109–122

23. BGOegg performance World best invariant mass resolution sMp, sMh, sMh’
7, 14, 19 MeV (Carbon)
8, 22, 30 MeV (LH2)
Y. Matsumura’s talk
h’ mesic nuclei search
h’ line shape study
h production

24. Performance of FG 2.9% energy resolution @ 1GeV
Nuclear Instruments and Methods in Physics Research A 447 (2000) 467}475

25. MC simulation for BGOegg+FG
Geant4 base MC simulation
FG Calibration
Energy resolution
BGOegg + FG
IPS, CDC + FGPS
gg invariant mass distribution : FG only

26. Simulation result improve the Forward region acceptance BGOegg+FG
BGOegg only
BGOegg+FG
BGOegg only
h’ -> gg yield
f1(1285) -> pph -> 6g

27. Summary
BGOegg calorimeter experiments with H2 and carbon target was performed until 2016/07.
LEPS2 has one order of magnitude higher intensity beam and large acceptance coverage.
h’ mesic nuclei, baryon resonance, etc
FG PWO counter will be test in ELPH
We plan to build the BGOegg + FG setup as a next possible candidate.