Study of double-λ hypernuclei

Transcription

1 Study of double- hyernuclei Our goal Phys. Det., Gifu Univ. K.Nakazawa Status of exeriments Exeriment at J-PARC Summary---statistics

2 Exerimental motivation Making a nuclear chart of double-hyernuclei => Information - force,. for understanding B-B int. in SU(3)f investigating Multi-strangeness system, strange matter Existence of the H-dibaryon resonance? Couling effect

3 Theoretical rogress B To know int. indeendent on the core structure, we need to measure A-deendence of B.

4 Nuclear Chart with Strangeness Our goal is making a S=-2 nuclear chart, by observing so many nuclei with S=-2. Flavor Nuclear Physics C=2 C=1 3000/7000

5 Status of exeriments S.Aoki et al, PTP.85(1991)1287 M.Danysz et al., PRL.11(1963)29; R.H.Dalitz et al., Proc. R.S.Lond.A436(1989)1 D.J.Prowse, PRL.17(1966) Be in ~4 Ξstos B 9 if a doughter Be is in excited B 6 He??????? B 13 B KEK-E176 in ~80 Ξstos B 13 if a doughter C is in excited or 10 Be B B The existence of Double- hyernucleus was confiermed

6 1 Status of exeriments NAGARA event 6 He double-hyernucleus Unique interretation!! C He + 4 He + t 6 5 He He Double- hyernuclei from E373 H.Takahashi et al., P. R. L. 87, (2001) High Energy News Vol.20 No.5 (2002) KEK - Lambha 6 He 4 He mhe m Demachi-yanagi event two body case at oint A + 12 C 10 Be + t or 10 Be* + t or MeV MeV MeV three body case at oint A 1) + 14 N 13 B + + n MeV He t - C A ht t :// u.ac.j/toics/nagara-e.htm B

7 Status of exeriments Double- hyernuclei from E373 3 rd double- hyernucleus Nuclear secies of the double is erhas He, He or Be. B : interaction energy [MeV] interaction is attractive but weak

8 Statistics of exeriments via Ξ hyeron cature at rest Danysz, et al E % finished E #ofξ - sto ~4 ~80 ~10 3 Light nuclei with S= ~6 Twin single- 0 2~3 2 Quite oor statistics until now.

9 Nuclear Physics with double strangeness (S=-2) KEK-E373 => AGS-E964 Beam : K - (1.7GeV/c), 4 x 10 5 K - /sill with K - /π - >9 at D6-line Detectors : Nuclear Emulsion, Double-sided Si stri Detector (DSSD), Ge-Detector (Hyerball), KURAMA magnet Time requested : 150 hours for detector tune 600 hours for beam exosure (K-, K+) trigger 10 4 Ξ - stoing events We requested Beam time on FY2006

10 Ge detector for Ξ-atomic X-ray

11 n Double-Sided Si Detector

12 Develoment of Automatic Scanning Images are shown: 1. Surface detection => Grid measurement for osition calib. 2. Track scanning Current system Surface & Grid : 22 sec. Track_scan : 15 sec. Develoing system Surface & Grid : 9 sec. Track_Scan : 6 sec.

13 Develoment of grid rinting to get better osition accuracy Fabrication of samle mask from Korean Collaborators Size of mask : 15x15cm 2 Area of hole marks : 15 x 7.5cm 2 (half below) Base : Quartz crystal (3.2mm thick) Coated material : Chrome (10 µm thick) Ga distance of each marks : x: 99.6 µm, x: 99.3 µm Hole size : 0.89 µm φ

14 Mask holes We will have recise calibration oints Exosed image in X-ray film 100µm by 20 obj. lens by 20 obj. lens Exosure time : 1 sec UV wave length : 255 nm Distance from source to trget : 30cm

15 New Hybrid-Emulsion Exeriment at J-PARC (no K + tracking x 2) K - +(,n) X : 3.5times & Em.: Outline : No K + tagging no sectrometer magnet Trigger K C reaction X-ray(FD)

16 New Hybrid-Emulsion Exeriment at J-PARC To get double- hyernucleus via Ξ stoing events Information: nuclear chart of S=-2 nuclei -ray from double- hyernuclei Develoments : Hyerball fully automated scanning system nuclear emulsion itself next seaker () roosal will be submitted.

17 SEM Micrograhs of AgBr Grains E373 emulsion (ET-7C,D) SEM : scanning electron microscoe NIT(Nano Image Tracker) develoed by Nagoya Fine grain emulsion crystal to get better osition resolution at J-PARC Size of AgBr Grains 200nm Size 40nm RMS 9nm

18 Tracks due to 5MeV - articles ordinal emulsion Dark Field Image of Light Microscoe NIT Fine grain emulsion crystal to get better osition resolution at J-PARC Develoment 1) density 2.8(g/cc) 3.5(g/cc) or 2) size : 40nm 70~80[?]nm Pions & fast rotons without beam tracks Higher dense exosure

19 Summary Comarison of yields Roughly estimated outcome 95% fin. future FY2006?