Status of J-PARC E07 Junya Yoshida J-PARC - PowerPoint PPT Presentation

Status of J-PARC E07 ： ダブル Λ ハイパー核検出実験の現状 Junya Yoshida J-PARC E07 Collaboration Physics department, Gifu University, Japan 15001001, 24105002z 1

Double strangeness nuclei: *Exotic nuclei made up of two s-quarks (lifetime =~10 -10 sec) *Tiny neutron-star on the ground X hypernuclei LL hypernuclei d -quark u -quark ｎ ｐ ΛΛ ｎ ｐ s -quark d -quark ｎ Ξ - ｐ ｎ ｐ ｎ s -quark s -quark 6 ΛΛ He ( 4 He + Λ + Λ) 15 Ξ C ( 14 N + Ξ - ) *Essential subject to understand baryon-baryon interactions and EOS of NS NN interaction ? range ? Λ N N N Ξ Λ ~1fm 2

Photographic emulsion sheet for double strangeness nuclei Sheet after photographic development Optical microscope CCD camera 25.0cm*24.5cm stage Objective lens （ x10,x50,x100 ） *Photographic film having sub-micron of special resolution *Thick sheets: T=~1mm -> ~0.5mm (after development) *7stages in Gifu-University and JAEA 3

Under 20x objective lens 100 m m micrograph 345mm 350mm … Emulsion sheet Thickness :1.0mm → 0.6mm after dev. Focal depth: 6 m m, equal to 18 m m before dev. 4

Under 20x objective lens 100 m m micrograph 345mm 350mm … Emulsion sheet Thickness :1.0mm → 0.6mm after dev. Focal depth: 6 m m, equal to 18 m m before dev. 5

Under 20x objective lens 100 m m micrograph 345mm 350mm … Emulsion sheet Thickness :1.0mm → 0.6mm after dev. Focal depth: 6 m m, equal to 18 m m before dev. 6

Under 20x objective lens 100 m m micrograph 345mm 350mm … Emulsion sheet Thickness :1.0mm → 0.6mm after dev. Focal depth: 6 m m, equal to 18 m m before dev. 7

Hybrid method for J-PARC E07, double strangeness nuclei search SSD SSD Emulsion stack (13layers) Cross section K + K - beam ~0.16 mb 1.8GeV/c X - ? Hypernuclei as nuclear fragment Diamond target Silicon Strip Detector(SSD) Emulsion stack K - beam 35cm*34.5cm*13layers 8

X capture Ξ - ｎ ｎ ｐ p + Ξ - → Λ + Λ + 28MeV ｐ ｎ ｎ Λ Λ ｐ Λ Λ ｐ ｐ ｎ Twin L hypernuclei LL hypernucleus ｎ ｐ ｎ Λ ｎ ｐ ｐ ｎ Λ ｎ ｐ ｎ ｐ ｎ Λ ｎ ｐ ｐ ｎ ｐ Λ ｐ ｎ π - π - ｎ ｎ ｐ ｎ ｎ ｐ Λ ｐ ｐ ｎ ｐ ｐ ｎ ｐ ｎ ｐ ｎ ｎ ｐ 9 ｐ ｎ

Kiso Event d -quark s -quark Ξ - ｎ ｎ ｐ s -quark ｐ ｎ M( A Z) + M X - B X Kiso event ： X - + 14 N ⇒ 1 0 Be + 5 L He L ｎ Λ ｐ Λ ｎ ｐ ｎ ｐ Bound state Ξ - and 14N with strong interaction ｎ ｐ ｎ ｐ B Ξ - = 1.11~4.38 +- 0.25 MeV M( L X) + M( L X’) + Qvalue PTEP. (2015) 033D02 . 2015 年 1 月 19 日 中日新聞 朝刊 r B X Λ 10

Nagara event ６ Λ Λ He ｎ ｎ ｐ d -quark ｐ ｎ s -quark 12 C Ξ - s -quark ｎ ｐ 6 Λ Λ He ｎ X - Λ ｎ ｐ ｎ ｎ ｐ Λ ｐ ｐ ｎ p + Ξ - → Λ + Λ + 28MeV 6 He 5 He r r ΛΛ Λ B Λ B ΛΛ Λ ΛΛ ｐ ｎ Λ π - ｐ ΔB ΛΛ = B ΛΛ - 2B Λ ｐ ｎ A Z) = M( A-1 Z) + M Λ - B Λ M( Λ A Z) = M( A-2 Z) + 2M Λ - B ΛΛ M( ΛΛ ｎ LL interaction is weekly attractive ｎ ｐ ΔB ΛΛ = 0.67 +- 0.17 MeV ｐ ｎ Where, B Ξ - = 0.13MeV 11

2000 年代までに 検出された事象数： 9 核種決定、質量再構成に成功した事象数：１ X - X - X X - - J-PARC E07 ： 過去 10 倍の統計量でダブルストレンジネス核を生成する実験 * Photographic emulsion gel 800kg → 2.1t * Purity of K- beam 25% → 85% * Automated Tracking in emulsion sheets *A = 6~17 LL hypernuclei : LL interaction, nuclear structure, LL - X N coupling. * X hypernuclei ( X - - 16 O, X - - 14 N, X - - 12 C ): X N interaction, LL - X N coupling. 12

First measurement of X-ray from X -atoms Ag(n=8, l=7) → (n=7,l=6) Ξ - V r X-ray Ξ - 107 Ag Ge detector Hyperball-X 60 511 keV 50 Shift Width Z(n,l) E (keV) Counts/2 keV (keV) (keV) Ag(370 keV) 40 Ag(8,7) → (7,6) 33 counts Br(316 keV) Case 1 370.45 0.28 0.15 30 18 counts Case 2 3.3 0.79 20 Br(7,6) → (6,5) Case 1 315.5 0.73 0.44 10 Case 2 5.5 1.74 0 Case 1: assuming potential shape to be the same 0 100 200 300 400 500 600 700 800 as the nuclear density ( t r potential ) Energy (keV) Case 2: Nijmegen D model correcting to produce the potential depth of ~ 14 MeV. Simulated for X - -stopping for 10 4 events in the Emulsion • • Energy resolution for Ge : 2keV FWHM Statistical accuracy of shift energies : Br(316 keV): 400 eV, Ag(370 keV): 200 eV 13

KURAMA spectrometer for E07 TOF wall KURAMA Magnet SSD Diamond target Ge detector: Hyperball-X Emulsion stack 14

“Emulsion mover” for J -PARC E07 target Emulsion cassette SSD K - beam 1.8GeV/c Beam size ： ( s X, s Y) = ~(10, 6)mm * Track density = 10 6 /cm 2 （ Observable limit ） * Sliding emulsion stack spill by spill * 6hours / stack 15

“Emulsion mover” for J -PARC E07 target Emulsion cassette SSD K - beam 1.8GeV/c Beam size ： ( s X, s Y) = ~(10, 6)mm * Track density = 10 6 /cm 2 （ Observable limit ） * Sliding emulsion stack spill by spill * 6hours / stack 16

2014 2015 2016 2017 Emulsion sheet making -> in Kamioka mine 2015 May. Test experiment 2015 Oct. Commissioning run Refreshing 1 st physics run Beam exposure *Commissioning Photographic Dev. *18 modules Analysis Jun. 30 th , 2016 ~60% 2 nd physics run Refreshing Beam exposure *Commissioning Photographic Dev. *100 modules 17

drying room The emulsion facility at Gifu University pouring room Tanks for photographic development 18

Emulsion pouring Flattened base-film by vacuum Pouring yard Drying 28 degrees Celsius, 75% R.H., 2days !!Mock-up!! Pouring melted nuclear emulsion 19 40 degrees Celsius, 3.1kg

Lead shield in Kamioka mine In a refrigerator in Gifu Univ. : ~400days Cooling at 17 o C. 100µm 20 In Kamioka mine. : ~400days

Refreshing Compton-elec. Tracks / (100mm) 3 *Beam exposure 88.6 +- 3.4 *Photographic dev. 48.1 +- 2.5 Refreshing: ・ 4days in Temp.:25 deg C, Humi.: 90 % ・ humidification 2days + 4days + drying 2days ・ 4Ag + O 2 + 2H 2 O -> 4Ag + + 4OH - Temp ： 25 ℃ R.H : 90 % Refresh chamber capacity :100 sheets !!Mock-up!! 21

Photographic development (Thin + 11Thick + Thin)*18stacks for the 1st physics run, 2016 Jun.- Aug. timetable drying washing preparation presoak, dev. fix presoak, dev. next cycle -> preparation fix 1day Emulsion sheet after photographic dev. 350*345mm 2 In washing 22

K + tagging: momentum and missing mass measurement by KURAMA *Momentum resolution : 1.4% *Missing mass resolution: ~14MeV/c 2 reconstructed X - mass: 1319.5 +- 14.2 MeV/c 2 with SSD X - tagging *K + yield : 1.03*10 5 events in 17.5 stacks in 1 st physics run p X - mass peak in CH 2 target run d K - p + K + missing mass(CH 2 target) p - 23

‘ p ’( K − ,K + ) X - event reconstruction tan q x_missing_mom. – tan q x_ X track Stack SSD Target - data - simulation K + K - beam X - 1.8GeV/c missing momentum SSD dE *Kinematics is consistent with simulation K + *Yield of X - stop event 1.6*10 3 events in 1 st run 12.2*10 3 events in 2 nd run X - candidates 13.8*10 3 events (Total) dE (arb. unit) 24

Alignment of SSD & Emulsion sheet With pattern matching of p-bar beam tracks SSD - beam p SSD Pattern matching Emulsion SSD 1 st emulsion sheet 1 st emulsion sheet （ after development ） （ before development ） ~10 4 /cm 2 Pattern matching - dy:dx X-projection y-projection Y[mm] s x =21 m m s y = 22 m m 25 X[mm] Y[mm] Mod: 004-RightUpCorner X[mm]

Track following : In Operation. • SSD-pl01 connection • beam pattern matching for adjacent sheets • image taking around stopping point Found events X - -> Lp - Decay Stop w/o fragment stop 10 m m stop X - -> Lp - Decay Beam direction

Event reconstruction in emulsion sheet 2 3 P.R.L. 87, 212502 (2001) * Track measurement: range, theta and phi * Initial state: bound system 12 C or 14 N or 16 O and Ξ - * Selection possible decay modes. Conservation of charge, energy, momentum, Nbaryon, Nstrangeness etc. * PID with grain- density and “track boldness” * PID with Multiple Coulomb Scattering 27

A lpha decay event search by “Vertex - picker” “Overall scanning” Finding vertex-like objects with image processing Cross-tracks 212 Po (8.785 MeV) vertex-like objects Classification Beam Intl. Alpha decay *96% accuracy for 3 categories Density and Shrinkage measurement 28

E07 実験はこれから収穫期に入る * Spectrometer system is well working * Successful establishment of Hybrid-Emulsion method for E07 *Emulsion analysis has just started. * Expected Xi stop event: 14*10 4 We will detect NEW ONES 29

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pattern matching pattern 2 pattern 1 …. …. * Put the both pattern on a temporary field. * Draw vectors for all the combination. peak detection in 2D histogram 31

X - particles Through EnergyLoss->Stop InFlightDecay Hadronic Int. X - -> Lp - (BR:99.9%) Physics process AtomicState->Capture NoFragment WithFragment r stop s stop 2ry vertex InFlightDecay Topology r stop+AugerElectron s stop_SingleHyper s stop_Twin s stop_DoubleHyper 32