2. Super fragment search in CHORUS I Progress note after the last Nagoya meeting (Apr-’02) II Hyper fragment candidates III An event with 3 vertices Overview of the event pβ measurement IV Efficiency of image analysis Vertex finding efficiency Black finding efficiency V Plan of paper

3. Progress note after the last Nagoya meeting (Apr.-’02) after Apr-’02Before Apr-’02 #images analyzed Run 96 50.0K(39.2K) Run 97 48.9K(40.1K) 1ry found16.4K(12.1K)20.3K(14.8K) viewer check 5.3K(4.4K) 6.8K(5.7K) manual check 105 157 further analysis (track follow, range…) 22 17 Angle measurement of tracks of normal events 175 events 1564 tracks (818 thins, 78 grays, 668 blacks) Analysis to search super fragment Analysis to estimate efficiency

4. Multi-vertices events ( >2prong ) 1ry vertex2ry vertex MDTEventPl#PμPμ NsNgNb#brgFast PVisible E 22B5163113236u -9.851 43 14.9 27.1 21B5367374821u-13.82 74 16.9 30.9 +12B5383444429d-11.311104 26.8 61.7 47T5482179229d-14.531 32 10.7 12.2 *47T5643172813d -9.543142 38.6 38.9 *11T6040250717u-22.143124>15.2>30.23 vertices 12B6084371619u(-1.8)31102 13.9 26.6 35T6141391420d -5.852113 14.8 24.6 47T6149076428u-12.87 63 3.3 8.7 *35T6247184917u -3.793175 37.4 53.8 *26T6271056714u-17.662103>56.4>65.4 35T6438143609d-13.75 114 6.3 12.8 16B6594159105u-22.373122 13.8 24.9

5. Multi-vertices events ( 1prong or background? ) 1ry vertex2ry V MDTEventPl#PμPμ NsNgNb#brg 11T5015264621d-19.22?parent(=thin) + knock-on e? 21T5164240527d-10.41 16T5235312512u-10.71gray → 1black? 15T5750001327u-25.83?black + bg black? 31T5909227419u-21.63? black + bg black? 15B6492126412u-12.83161? Fast P=3.0(GeV/c) 21B6522033404d-21.1161 Fast P=6.6(GeV/c) 48T6080178828u-13.91 12T6904245420u-26.43?black + bg black?

6. 62471849 2 vertices 351 62471849 33 vz:533.4 atan(thy,thz) back lcal #dt atan(thy,thz) back lcal #dt v 3.939.929 4.3 2 g 1 -.344 -.076 96.6 2 b 2 -.816.533 39.2 2 g 2 -.460 -.132 103.1 2 b 3 -1.137.743 33.1 2 g 3 1.549.827 1 594.8 2 b 4 -.300 -.681 50.2 2 b 17.783 1.132 1 7.6 2 b 5.667 -.547 54.9 2 b 18.145.697 11.8 2 b 6.447.798 90.4 2 b 19 -.403.013 26.0 2 b 7 -.040 -1.289 71.8 2 b 20.631.000 1 17.3 2 b 8 -.406.840 147.7 2 b 21 -1.340 1.340 1 36.5 2 b 9 1.168 1.400 1 208.5 2 t 1.018.118 85.4 3 b 10 1.508 1.537 1 292.4 2 t 2 -.116.196 94.1 4 b 11.821.842 1 79.1 2 t 3 -.065.004 534.6 4 b 12.566.753 1 221.5 2 t 4.005 -.023 533.0 4 b 13 -1.054.968 1 176.4 2 t 5.227.463 103.5 3 b 14 -1.410 -1.311 1 203.6 2 t 6.303.605 116.5 3 b 15.965 -.291 7.1 2 t 7.197 -.301 84.1 5 b 16 -.426 -.208 1 114.9 2 t 8 -.442 1.039 95.1 3 t 9 1.347 1.486 75.9 3 b2 b3 b4 b5 b6 b7 b8 b9 b10 b11 b12 b13 b17 b15 b16 b14 b18 b19 b20 b21 g2 g3 g1 t1 t2 t3 t4 t5 t6 t7 t8

7. 62710567 2 vertices 261 62710567 21 vz:636.1 atan(thy,thz) back lcal #dt atan(thy,thz) back lcal #dt b 1 -.092 -.197 88.3 2 g 1 1.199 -1.237 228.7 2 b 2.574.534 65.7 2 g 2 1.182 -.900 292.6 2 b 3 -.165.887 88.0 2 b 11 -.167 -1.291 10.7 2 b 4 1.494 -1.543 1 221.7 2 b 12 -.335 -.215 32.6 2 b 5 -1.435 1.439 389.2 2 b 13.832 -.212 21.9 2 b 6 1.336 -.785 539.9 2 t 1.145 -.141 197.5 5 b 7 -1.336.700 1 127.3 2 t 2 -.052.053 195.3 5 b 8 -1.032.516 1 23.6 2 t 3 -.364.054 144.8 4 b 9 -.552 1.077 1 166.7 2 t 4 -.568.095 233.7 3 b 10.421.000 1 2.2 2 t 5 -.278.350 208.9 3 t 6 -.132.573 235.2 3 b1 b2 b3 b4 b5 b6b7 b8 b9 b11 g1 b12 b13 b14 g2 t1 t2 t3 t4 t5 t6

8. 56431728 2 vertices 471 56431728 24 vz:183.2 atan(thy,thz) back lcal #dt atan(thy,thz) back lcal #dt b 1.536 -.287 52.5 2 g 1.628.273 136.7 2 b 2.824.210 83.2 2 g 2 1.317 1.306 508.0 2 b 3.985 -.797 158.6 2 b 14 -1.270 -.306 3.4 2 b 4 -.140.652 88.9 2 g 3.208 -.172 36.9 2 b 5 -1.163 1.161 79.9 2 b 15 -.002 -.739 5.5 2 b 6 -1.261 -.979 51.3 2 b 16.248 -1.313 1 28.0 2 b 7 -1.140 -1.028 180.7 2 t 1.044.051 179.5 8 b 8 -1.292 1.428 1 231.0 2 t 2 -.149 -.044 180.2 8 b 9 -.729 -.216 1 120.2 2 t 3 -.280.619 148.4 8 b 10.948.249 1 148.1 2 t 4.542 -.302 224.1 6 b 11 -.439.435 1 101.2 2 b 12.458 -1.071 1 6.6 2 b 13 -.088 -.082 19.5 2 b 14 1.571 1.571 3.0 2 b1 b2 b3 b1 6 b4 g1 b5 b6 b7 b8 b9 b1 0 b11 b15 g2 g3 t1 t2 t3 t4

9. 53834444 2 vertices 120 53834444 18 vz: 79.6 atan(thy,thz) back lcal #dt atan(thy,thz) back lcal #dt b 1.215.102 82.3 2 b 1.210.099 21.7 2 b 2 -.212.039 80.9 2 b 2 -.174.046 13.3 2 b 3 1.529.569 120.9 2 g 1.147 -.022 45.8 2 b 4.348 -1.062 1 110.5 2 b 11.115.093 30.5 2 b 5.245 -.874 1 161.0 2 b 12 1.150.578 22.9 2 b 6.535 -.625 1 196.8 2 b 13 -1.002 1.149 20.4 2 b 7.854 -.920 1 48.5 2 b 14 -.116 -.542 1 20.1 2 b 8.725.505 1 82.9 2 t 1.074 -.010 74.6 4 b 9.338 1.032 1 221.1 2 b 10.548 -.461 9.0 2 b1 b2 b3 b4 b5 b6 b7 b8 b9 b11 b12 b13 b14 g1 t1

10. 60402507 3 vertices V2 V1 V3 60402507 with 3 vertices 11t pl.17 ～ 1134μm

11. 60402507 sketch and data 111 60402507 23 vz:735.1 atan(thy,thz) back lcal #dt atan(thy,thz) back lcal #dt b 1.603 -.030 28.2 2 b 11.614 -.152 9.6 2 b 2 1.412 1.147 110.0 2 b 12.902 -.712 3.7 2 b 3.694.255 211.0 2 b 13 1.571 1.571 15.1 2 b 4 1.350 1.398 553.8 2 b 14 1.571 1.571 40.1 2 b 5 -1.570 -1.474 159916.7 2 b 15 1.571 1.571 25.2 2 b 6.952 -1.321 1 173.7 2 t 1 -.002 -.009 290.9 19 b 7 -.039 -.052 736.3 2 t 2 -.035.043 295.8 22 b 8 -.130 -1.204 213.7 2 t 3 -.324 -.840 458.9 4 b 9 -.298.853 1 85.7 2 t 4 1.400 1.383 1 447.9 3 b 10.602 -.394 3.7 2 b 15 1.447 1.532 1 51.3 2 g 1.243.066 151.1 2 g 2.210.319 147.9 2 g 3.325.926 1 97.1 2 b1 b2 b14 b3 b4 b5 b6 b15 b7 b8 b9 b12 b13 g1 g2 g3 t1 t2 t3 t4

12. 60402507 sketch zoom A likely interpretation V3 is σ-star ( π - capture ), if pβof #4 is 13MeV/c (estimated from range) at V2. Then, V2 is a mesic decay of hyper fragment. … is excluded because #4 looks like more energetic. If #4 is π －, change in direction by scattering is almost same as the end of π + decay in emulsion.

13. Black 15 11T 60402507 pl.17u L ～ 1134μm pβ (E) (MeV) I/I0 π 13.1 ( 6.7) ～ 5.4 K 22.8 (11.6) ～ 9.4 P 30.2 (15.2) ～ 12 D 40.5 (20.3) ～ 17 T 47.8 (24.0) ～ 20 b15 (was track#4 in the previous figure)

14. An example of π + → μ + → e + decay 71B 78902354 pl.19 Pl.19up π+π+ π+π+ μ+μ+ μ+μ+ e+e+ A B AB ～ 610μm Compared scattering of the end of π + with track #4

15. MDT71B 78902354 pl.19 π+ → μ+ → e+ (No.1) Measured data

16. Pβ measurement position along a track

17. Pβ measurement 11T 60402507 pl.17u Measured data

18. Pβ measurement 11T 60402507 pl.17u

19. Preliminary pβ of black15 K-K- PΣ－Σ－ Deuteron 3 Λ H(pnΛ 0 ) PβPβ range I/I0rangeI/I0rangeI/I0rangeI/I0rangeI/I0 50 4.61 5.1 2.73 8.4 2.29 10.2 1.6314.3 1.17 20. 60 6.42 4.4 3.83 7.3 3.16 8.8 2.2512.51.60 17.7 70 8.51 3.9 5.05 6.5 4.16 7.8 2.9411.12.08 15.8 8010.63.56.425.85.287.03.7210.02.6314.3 Measured at μm rad pβ(MeV/c)(#data) first 500μm (i = 1, 4)3170.016572(4) last 500μm (i = 10,13)3230.020458(4) Measurement result ( ⊿ L i ＝ L i+5 – L i, ⊿ θ i =θ i+5 – θ i ) Table pβ - range(mm), I/I0 correlation (expected value theoretically) No calibrated data now. It will be made later. Accuracy is unknown.

20. Possible interpretations V1 V2 V3 A B AV2BV3consistency K－K－ capture 3 Λ H (pnΛ 0 ) mesic decay 3 Λ H → p+n+p+π － An expected fast π - is not observed. K－K－ Interaction with two nucleons K － +p+n → Σ － +p K － +p+p → Σ － +n Σ － captureIs feature consistent with Σ － capture? SuperFdecayK －, Σ － captureConsistency? Further analysis is required. Pβ calibration, ionization …

21. 415 images (362 events) (22t pl.21,22,23 36t pl.15,16,17 71b pl.20,21,22) search vertex in a fiducial volume with image viewer 175 events Vertex found between frame#9 and #40 Measured angle of all tracks in emulsion manually 1564 tracks compare manual check and image analysis 108 vertices found by image analysis 272 blacks found Analysis for efficiency estimation 818 thin 78 gray 668 black 350μm fr# 1 9 40 48 ～ 60μm

22. Ns, Nb Distribution (nearly no biased)

23. Track angle distribution (nearly no biased)

24. Vertex finding efficiency vs. Ns

25. Vertex finding efficiency vs. Nb

26. Vertex finding efficiency vs. vertex position

27. Black finding efficiency vs. direction cos θ （ angle to the beam) A: all blacks B: blacks which vertices are found by image analysis C: blacks found by image analysis

28. Black finding efficiency vs. azimuthal angle (Φ)

29. Summary of finding efficiency finding efficeiency Vertex 62 % (for all events) 71% (Nb ≧１） Black track 41% (for all events) 65% (for events which 1ry vtx found by image analyisis)

30. Plan of paper ・ Upper limit of Super fragment production ・ Hyper fragment production in νint. Production of strange particle in ν cc int. (relative ratio) νd (v) →μ － u+ss (14%) νd (s) →μ － u+ss ( 1.7%) νu →μ － d+ss ( 0.6%) Production of charmed particle in ν cc int. νd (v) →μ － c ( 3.7%) νd (s) →μ － c ( 0.4%) νs (+s) →μ － c (+s) (2.8%) Others νd (v) →μ － u+(uu or dd) (57%) νd (s) →μ － u+(uu or dd) (17%) νμνμ μ－μ－ W+W+ s s νμνμ μ－μ－ W+W+ c Non-leading s-quark goes to strange particle or hyper fragment Leading c-quark goes to charm particle or super fragment d,u u,d d,s

31. 50.0k images (39.2k events) in ’96 run are analyzed 12.1k 1ry vertices found by image analysis 13 Multi-vertices events found (2ry with >2prongs) 12 events with 2-vertices 1 event with 3-vertices Hyper fragment candidates 3 events with fast proton 2 events with visible energy ≧ 30MeV Summary Future plan Increase statistic of track slope data to estimate efficiency Pβ calibration (compare pβ obtained form range and from scattering measurement) Make sure identification of hyper fragment Background estimation present preliminary result for a paper by the end of October (if possible) Concurrently reanalyze images with improved program