1. Analysis of Light Single-  Hypernuclei Events in Nuclear Emulsion Detected with Overall-scanning Method MYINT KYAW SOE, Kazuma NAKAZAWA, Kaoru HOSHINO, Hiroki ITO, Kazunori ITONAGA, Hidetaka KOBAYASHI, Yoko ENDO, Junya YOSHIDA, Khin T. TINT, Shinji KINBARA, Akihiro MISHINA  Introduction  Review experiments for Life- time of  3 H Outline 30/11/2014 1  Nuclear Emulsion  Searching 3  H hypernucleus events in nuclear emulsion Gifu University Japan  Estimation of mesonic decay events  Summary

2. Introduction 2  3 H  is the most basic and simple hypernuclear bound system among hypernuclei n n   p p B  = 0.13 ±0.05 MeV So far its life-time estimated by any experiments has large interval in each other Life-time for  3 H are estimated by experiments In order to provide precise information of life-time and B   with small error for  3 H high statistics events for  3 H are requiered Less than and nearly 180 ps Aim is to measure the life-time and B  of light single-  hypernuclei with nuclear emulsion experiment

3. 3 Review experiments for Life-time of  3 H 1) Counter experiments HypHI collaboration [1] 6 Li+ 12 C at 2A GeV Observed the life-time for  3 H : 183 +42 -32 ± 37 ps & for  262 +56 -43 ± 45ps STAR at BNL RHIC [2] 197 Au+ 197 Au Observed lifetime for 3  H, 138 +26 -22 ps Above two counter experiments inform the life-time of 3  H is shorter than that of free  and their estimation interval is large [1] C.Rappold et al. Nuclear Physics A913 (2013) 170-184 http://kds.kek.jp/getFile.py/access?contribId=18&sessionId=40&resId=0&materialId=slides&confId=15455 [2]

4. 4 2) Emulsion experiment [3] Emulsion stacks are exposed by 2.3 and 2.5 GeV/c2 K - 3  H → 3 He +   (3 in-flight and 1 at rest decays) Observed the life-time for 3  H : 0.9 +2.2 -0.4 ×10 -10 s If life-time of 3  H is shorter than free  B   of 3  H may be reconsidered Life-time of 3  H(<=180 ps) should be nearly equal to that of  ps  because B  is very small Expect to confirm information of life-time with many statistic events in nuclear emulsion [3] R. J. Prem and P. H. Steinberg, Physical Rev. vol136,number 6 B, Dec,1964

5. Nuclear Emulsion Emulsion are composed of 8 materials and AgBr is the large amount of them AgBr crystal Microscopic image The best detector for the short-life nuclei The charged particle loss their energy according to the ionization along their ranges traveled in emulsion Ranges can be transformed into Kinetic energy with When charged particle passed through emulsion After photographic developing 5 Latent image

6. 6 Searching 3  H hypernucleus events in nuclear emulsion 3  H → 3 He +    two body decay  3  H → 2 H + 1 1 H +    three body decay   3H3H 3 He  3H3H 2H2H 11H11H  3H3H Inflight decay At-rest decay Schematic topology of 3  H decay in emulsion To get many statistics of 3  H events (more than 5×10 2 events) Detect events in emulsion plates of KEK-PS E373 experiment by Overall-scanning method presented by Dr. J. Yoshida

7. Emulsion plate Eye check events in 3 dimensions under microscope X y z Output images from overall-scanning Automatic scanning Event detection 7

8. Event categorization Single candidate eventsUranium decayed series Beam interaction Thorium decayed series Hammer track And so on By seeing topology of events, the event types are classified as Among single hypernucleus events, mesonic decayed events for 3  H have to choice 8

9. 9 Estimation of mesonic decay Overall-scanning detect full volume of emulsion plates Even the test scan of overall-scanning, we found the two mesonic decay events for candidates of  3 H from (3cm×3cm) scan area #1 #2 #3 #4 #1 #3 #2 #4 We estimate mesonic decay events nearly 100 in one plate (25×24.5)cm 2 Beam

10. 10 Construction of invariant mass range, angle theta and phi of daughter particles Kinetic energies & momentum Invariance Mass Our measurement result will be checked with consistence of other experiments From the measured invariant mass, range, momentum, B  and life-time are estimated

11. 11 Summary Reviewed experiments for life-time of  3 H, their estimation interval is large To provide and confirm precisely B  and life-time of   3 H, high statistics of  3 H candidates are searched The emulsion plates of KEK-PS E373 experiment are detected with overall-scanning method We estimate the mesonic decay events nearly 100 for the candidates of  3 H in one emulsion plate The precise information of Life time and B  of  3 H will be estimated from the invariant mass constructed with emulsion data

12. Measuring mass of single-  hypernucleus The mass of single hypernucleus can be constructed from momentum and energy of daughter fragments Kinetic energy of daughter particles Ranges of daughter particles in nuclear emulsion with range- energy relation Momentum of daughter particles Image of single candidate event Before analysis, the range and energy should be calibrated 12

13. 13 Range-Energy Relation depend on density and shrinkage factor of nuclear emulsion plate Calibrated by using monochromic  particles Range-energy Calibration shrinkage factor (S) = thickness of emulsion plate at beam exposure thickness of emulsion plate at measurement

14. Range distribution of  particles decayed from 212 Po Compare with linear equation, Range of  particles as; Where, S = shrinkage factor S = 2.29 ± 0.01 R = 48.94±0.30  m By using the well known energy 8.484MeV Density of emulsion = 3.75 ± 0.14 g/cm 3 Range→ Kinetic energy → momentum 14

15. y z x By fitting of the data points in linear on x-y plane and x-z as y = a x + b z = c x + d parameters a, b, c, d are obtained The parameters are fitted by  2 liner fitting method By the use of constraintsH i = y i -ax i -b H i = z i -cx i -d Minimizing with respect to , and z Where; Measuring angles  and  of tracks Momentum, ,  of tracks are known 15

16. B  of single-  hypernucleus From measured mass of sinlge-  hypernucleus, B  will be obtained as The Life time (T) can be measured from the range (R) and momentum(P) as Life-time of single-  hypernucleus 16

17. Introduction Aim is to measure B   and life-time of light single-  hypernuclei precisely with nuclear emulsion So far the error of B  of light single-  hypernucleus  such as  3 H  is large since the number of events is a few Overall-scanning method detect full volume of emulsion plate (Already presented by Dr. J. Yoshida) To search many number of single-  hypernuclear events, emulsion plates of KEK-PS E373 experiment are detected with overall-scanning method Recently, counter experiment suggested the life-time of   H is smaller than that of  hyperon Life-time of   H will be confirmed with nuclear emulsion experiment 17

18. Summary The emulsion plates of KEK-PS E373 experiment are detected with overall-scanning method to search many number of single hyper events The mass of singe nucleus is measured from the kinetic energy and momentum of daughter fragments Range and energy is calibrated with the tracks of alpha particle decayed in thorium and uranium series. B   and life-time will be measured from the constructed mass, range and momentum of single hypernucleus in nuclear emulsion 18

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