1. Status of E03 and E07 Kiyoshi Tanida Seoul National University
Sep. 23, 2011
Kiyoshi Tanida
(Seoul National University)

2. S=-2 systems in J-PARC
E03： Measurement of X rays from X- atom Spokesperson – K. Tanida (Seoul)
E05: Spectroscopic study of X-hypernucleus, 12XBe, via the 12C(K-,K+) reaction (Day 1 – 1st priority) Spokesperson – T. Nagae (Kyoto)
E07: Systematic study of double strangeness system with an emulsion-counter hybrid method
Spokespersons – K. Imai (JAEA)
K. Nakazawa (Gifu)
H. Tamura (Tohoku)
E03
E05
E07

3. E03 experiment World first measurement of X rays from X-atom
Gives direct information on the XA optical potential
Produce X- by the Fe(K-,K+) reaction, make it stop in the target, and measure X rays.
Aiming at establishing the experimental method K- K+ X-
X ray
Fe target X-
(dss) Fe
X ray

4. X atom level scheme X ray energy shift – real part
l=n-1 (circular state) X
l=n-2
l=n-3
...
Energy (arbitrary scale)
... Z
nuclear absorption
... X
... Z
l (orbital angular momentum)
X ray energy shift – real part
Width, yield – imaginary part
Successfully used for p-, K-,`p, and S-

5. Experimental setup K- K+ 1.8 GeV/c 1.4x106/spill (4s)
Long used at KEK-PS K2 beamline (E373, E522, ...)
Minor modification is necessary to accommodate high rate.
Large acceptance (~0.2 sr)

6. X-ray detector Hyperball-J Detection efficiency High-rate capability
30 Ge detectors
PWO anti-Compton
Detection efficiency
16% at 284 keV
High-rate capability
< 50% deadtime
Calibration
In-beam, frequent
Accuracy ~ 0.05 keV
Resolution
~2 keV (FWHM)

7. X-ray energy calibration
Goal: 50 eV accuracy
Difficulties:
Huge background single rate: <1 kHz (off-beam)  ~50 kHz (in-beam)
Rate dependent peak position shift (~1 keV) and peak broadening

8. peak position shift (using 20kHz electron beam)
beam off
peak position shift
~2ch = ~500eV
beam on

9. X-ray energy calibration
Goal: 50 eV accuracy
Difficulties:
Huge background single rate: <1 kHz (off-beam)  ~50 kHz (in-beam)
Rate dependent peak position shift (~1 keV) and peak broadening
Source position dependence of g-ray energy (~100 eV)
Solution:
Simultaneous calibration using triggerable source. Ge Ge
source

10. Calibration procedure
Put source on the side of Ge
Calibrate position dependence
Make sure g-ray energies of (other) standard sources at the target position are reproduced
Especially for in-beam
Take source data continuously
Peak shape and position may change with time
Peak drift, radiation damage.
Need enough events every a few hours.
E03: LSO scintillator
contains 176Lu: 202 keV & 307 keV Ge
target
source

11. Other active sources LSO: only 2 major g-rays – 200～300 keV
Wider range?
CsI with radioactive isotopes, such as 133Ba, 134Cs...
produced by Kyungpook National University, Korea
133Ba (0.12 mCi) embedded in CsI

12. CsI spectra γ-ray Energy by Ge CsI Efficiency (%) 81 45 276 74 303 75
356 73
383 58

13. E07 LL Hypernuclei Hybrid emulsion method Goal:
10000 stopped X- on emulsion
100 or more double-L HN events
10 nuclides
Chart of double-L hypernuclei

14. Production of LL hypernuclei
~10% of LL are
trapped in nuclei
Xp  LL

15. Example event in emulsion
Track length, thickness
PID/energy
Presume what are produced at each vertex
Then check consistency
Unique assignment is sometimes possible
Calculate binding energy DBLL = BLL - 2BL gives net LL interaction

16. Systematics of LL binding energy
DBLL may be different for each nucleus
For example by hyperon mixing effect
5LLHe
6LLHe p n L p n L p n X p n X
Suppressed
Enhanced

17. DSSD K+ K- Ξ- ΛΛ
Track down X- accurately in a narrow region

18. Old and new DSSD Old DSSD: Made ~7 years ago
Mistake in fabrication?
Only one works now
Readout by VA chip. Slow.
New DSSD: Under development in Korea
Sensor designed by Kyungpook Univ.
Fabricated at SENS company
Fast readout using APV25 chip with zero suppression
Details by Joo Changwoo.

19. Emulsion Got new grant – “Kiban S”, 5 years, ~2-oku yen
Emulsion can be purchased!
Make a new emulsion handling facility at Gifu University
Image development
Microscopes for analysis

20. General scanning If vertexes are found
 See again with x100 object lens  Human eyes
Original photo
vertex search
tracking
Binarize
Huff trans.

21. General scanning II Scan all images in emulsion
not only events selected for (K-,K+)
 ~100 times more statistics
Faster camera: 100 Hz  1 kHz
lens must move fast, too.
Observe larger volume at a time
Object lens: x50  x20
>100 times faster in total. (< 1s for 0.25 mm x 0.25 mm  < 1 month for one emulsion mod.)

22. Run plan (hopeful) Beam time will be available in 2013-2014.
Run both E07 and E03 in this period
Expected primary beam intensity will be 50 kW or ~20% of nominal intensity
Enough for E07  we will perform E07 first.
E03: may be accumulate only ~10% of statistics
E03 with smaller statistics
It’s possible to observe X ray, at least for 76 transition (though no physics information in this transition)
65 transition can be observed if G < 3 keV
Statistical error for DE will be larger by ~3 i.e., ~0.2 keV
Significant result will be obtained if G~DE~1 keV

23. Summary E03 and E07: experiments to challenge S=-2 world
Using common spectrometer system (KURAMA)
E03: X atomic X-ray
energy calibration is a key
LSO system is already developed
Developing other active sources for future experiments
E07: Search for double-L hypernuclei with emulsion
Got a large grant to purchase emulsion
Developing new DSSD in Korea
Emulsion general scanning is under development to further increase statistics.
Hopefully to run in