Scanning systems for double strangeness nuclei in nuclear emulsion Junya Yoshida Hiroki Ito, Shinji Kinbara, Hidetaka Kobayashi, Daisuke Nakashima, Kazuma Nakazawa, Myint Kyaw Soe, Aye Moh Moh Theint and Khin Than Tint Physics department, Gifu University, Japan ,

ｎ ｎ ｐ ｐ ｎ Ξ-Ξ- ｎ ｐｎ ｐ ｎ ｎ ｐ ｎ ｐ ｐ ｎ ｎ ｎ ｐ ｐ ｎ Λ ｐ π-π- ｎ ｐ ｐ ｎ Λ Λ #1 p + Ξ - → Λ + Λ + 28MeV a tiny characteristic shape having 3 vertexes Range of the track of Double lambda hypernuclei is about 10 microns in solid -> Nuclear emulsion d -quark s -quark a nucleus in nuclear emulsion. 2 ~10  m Double Lambda hypernucleus, Exotic nucleus made up of two Lambda hyperons Important subject to understand B-B interaction.

3 Nuclear emulsion plate for double strangeness nuclei (after photographic development) *Photographic film having sub-micron of special resolution *They record the tracks of charged particles passing through an emulsion film. *The size of a plate: 25cm*24.5cm *Thickness : ~1mm (before development) -> ~0.5mm (after development) KEK-PS E373’s emulsion plate

in ～ 80  - stops KEK-E176 KEK-E373 S.Aoki et al., NP. A828 (2009) ～ 10 3  - stops NAGARA -- MIKAGE -- HIDA -- DemachiYanagi -- -- M.Danysz et al., PRL.11(1963)29; R.H.Dalitz et al., Proc. R.S.Lond.A436(1989)1 in ～ 4  - stops List of double hypernuclei 4 D.H.N in 7 samples by E373 (expected)  ～ 10 4  - stops  ~ 10 2 Double ~ 50 Twin-hyper J-PARC Our knowledge on  -  interaction 4 Nakazawa, K., Takahashi, H., Prog. Theor. Phys. Suppl. 185, 335. Ahn, J. K. et al., Phys. Rev. C 88,

5 Diamond target  K  (p>1.0GeV/c) KK Double Lambda Hypernucleus Emulsion stack * Latent events (~10 times) may be recorded. How we obtain more double lambda hypernuclear events? A new Experiment: J-PARC E07 A new searching method: Overall-scanning method yield: ~30% KK  KK (K -, K 0 )

Concept and Key technologies; (1). 3-dimensional scanning under optical microscopic view. (2). Image process to find multi-vertex shape in emulsion. vertex–like shapes which consist of several black tracks Exhaustively 3D scanning “Overall-scanning method” by the “Vertex Picker”

7 high resolution CMOS 2048*358 pixel high frame rate 800fps wide F.O.V. x20 dry lens (NA0.35) 1142*200 micron 2 Piezoelectric drive stroke500 micron period5Hz picture40picts /cycle Continuously stage moving (1). Vertex picker （ Stage#7,8 ） emulsion plate objective lens Piezoelectric drive camera Designed speed: 10mm*10mm*0.9mm / 2min. = ~40 (340*335*0.9[mm 3 ]) To accomplish scanning of ~1000 films within a few year.

8 Difference of Gaussian Binalization Gaussian filter Original image Filter for bold tracksThinning Prob. Hough Trans.Vertexing kernel size = 17pix x20 Objective (NA0.35) 1 pix = ~0.56 micron threshold ~= peak*0.2 dist-edge-to-edge < 18pix N_Tracks > 3 polygon area > 650pix resolution = 1degree lemgth > 13 pix / line contour length > 5pix area > 10pix (smoothed – source) if negative, brightness=0 (2). Image process J.Yoshida et al., JPS Conf. Proc., (2014)

9 Extracted images, which contain at least a vertex-like-object Nagara event Kiso event One-vertex, beam interaction in emulsion /10mm*10mm*0.9mm Passing through of unrelated tracks (non-vertex), 80% of detected object 10 4 /10mm*10mm*0.9mm

Exhaustively 3D scanning under x20 objective lens The second image taking under x50 objective lens *Higher resolution in X, Y and Z-axis *Good contrast *Automated picture taking was developed Superimposed

11 1 st selection x20 2 nd selection x50 preliminary One vertex: 213 -> 177 Cross of tracks: > 421 One vertex Cross of tracks Noise on surface *Most of one-vertex event were detected as in second recognition *On the other hand, cross-tracks were not. *Detail investigation is just started. No-vertex

* “Overall-scanning method” by the “Vertex Picker” 3-dimensional scanning under optical microscopic view. Image process to find multi-vertex shape in emulsion directly. Improvement of detection efficiency and S/N ratio is being carried out. The second image-taking and image-process under x50 objective lens It seems to be effective. Vertex picker is In operation. ~1000 two-vertexes event, single hypernuclear event ~7 three-vertexes candidates. A typical twin-single-lambda- hypernuclear event (Kiso) Acknowledgements *JSPS KAKENHI Grants Number *MEXT Grants Numbers , (Grant-in-Aid for Scientific Research on Innovative Areas 2404). 12 Nakazawa et al., PTEP 2015, 033D02 10  m

13 An optical microscope for emulsion scanning The range of motion: 35cm*34.5cm Objective lens: x4, x10, x20, x50, x100 and so on CCD camera: 512pix*440pix*50Hz The stage is driven by computer-controlled motors(X,Y and Z-axis) 7stages in Gifu-University Stage CCD camera Objective lens