Hypernuclear Spectroscopy with Heavy Ion Collisions (HypHI)

The HypHI Phase 0 experiment at GSI

Eunhee Kim1,2

for HypHI collaboration2

1 Seoul National University,2 GSI, Germany

1 ND2010 29April2010

Hypernuclei: Laboratory for baryon-baryon interaction with hyperon

In order to understand baryon-baryon interaction under flavor SU(3), we need to investigate interactions involving nucleons and hyperons. Information of NN(nucleon-nucleon) interactions mainly

obtained from NN scattering experiments. Lack of information on YN(hyperon-nucleon) and YY(hyperon-

hyperon) interactions

Difficulties to study YN and YY interactions by reaction experiments No hyperon target available due to short lifetime (Y ~ 10-10 s) Impractical to produce hyperon beams with proper energy

Hypernuclei are bound nuclear system with hyperon. Hypernuclei can be used as a micro-laboratory to study YN and YY

interactions.

s

ud

s

dd

s

ds

s

ss

0

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Interests in hypernuclear physics Structure and decay of hypernuclei at extreme isospin

Isospin dependence of YN and YY interactions Hypernuclear magnetic moments

Property of hyperons in nuclear medium

Hypernuclear radii Stability of hypernuclei

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Not possible with conventional hypernuclear spectroscopy

via the (K-, -), (+, K+) and (e, e’K+) reactions.

A project of hypernuclear spectroscopy

with heavy ion induced reactions on a stable target nucleus,

the HypHI project.

Reachable with heavy ion collisions.

HypHI project

Projectile

Target

Hot participant zone

Projectile fragment

Hypernucleus

Hypernuclear production in the HypHI project

Energy threshold ~ 1.6 GeV for production (NN → ΛKN)

- Stable heavy ion beams and RI beams with up to 2 AGeV can be achieved at GSI.

The produced hypernucleus has as large velocity as the projectile fragment.

Large Lorentz factor ( > 3) → longer lifetime → Hypernucleus in flight A new doorway for hypernuclear spectroscopy

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HypHI at GSI/FAIR: Concept of experiments

Time-of-Flight detectorsTrackersN-detectorK+ counter

Magnet

n

Residues

p,

K

-Hypernucleus

Mesonic weak decay : → -pNon-mesonic weak-decay: p → np

Produced hypernucleus close to projectile velocity Large Lorents factor > 3 c ~ 20 cm at 2 A GeV

target

Magnet

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Present hypernuclear landscape

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Known hypernuclei

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Phase 1 (2009-2017) at GSIProton rich hypernuclei

Known hypernuclei104 /week103 /week

Hypernuclear landscape with HypHI

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Phase 1 (2009-2014) at GSIProton rich hypernnuclei

Hypernuclear landscape with HypHI

Known hypernuclei104 /week103 /week

Phase 1 (2009-2017) at GSIProton rich hypernuclei

Phase 2 (2017-) at R3B/FAIRNeutron rich hypernuclei

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Hypernuclear landscape with HypHIPhase 1 (2009-2014) at GSIProton rich hypernnuclei

Phase 1 (2009-2017) at GSIProton rich hypernuclei

Phase 3 (201X-) at FAIRHypernuclear separator

Known hypernuclei104 /week103 /weekWith hypernuclear separatorMagnetic moments

Phase 2 (2017-) at R3B/FAIRNeutron rich hypernuclei

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Hypernuclear landscape with HypHI

Known hypernuclei104 /week103 /weekWith hypernuclear separatorMagnetic moments

Phase 0 experiment in 2009: Demonstrate the feasibility of precise hypernuclear spectroscopy with heavy ion beams (6Li beam at 2 A GeV on 12C target) Known hypernuclei

104 /week103 /weekWith hypernuclear separatorMagnetic moments

Phase 1 (2009-2014) at GSIProton rich hypernnuclei

Phase 1 (2009-2017) at GSIProton rich hypernuclei

Phase 3 (201X-) at FAIRHypernuclear separator

Phase 2 (2017-) at R3B/FAIRNeutron rich hypernuclei

Phase 0 experiment To demonstrate the feasibility of the experimental methods of the HypHI project

with 6Li beams at 2 A GeV by producing and identifying light hypernuclei

3H → 3He + -

4H → 4He + -

5He → 4He + p +

-

▶ Beam: 6Li at 2 A GeV with an intensity of 5 x106 /s▶ Active Target : 12C with a thickness of 8 g/cm2

⊙ magnet direction

(0.75 T)

3days in Aug. and 11days in Oct. 2009

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ALADiN magnet

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(0.75 T)

TOF start (Time-of-flight start)

▶ For beam particles▶ Plastic fingers + small PMTs

: 1 MHz beam rate per finger▶ Time resolution: ~ 200 ps

5cm

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Scintillating fiber detectors

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▶ 4352 fibers with a diameter of 0.83 mm

▶ HAMAMATSU H7260KS MOD readout

▶ X and Y tracking : Position resolution: 0.46 mm (RMS)

▶ For secondary vertex triggerD. Nakajima, B. Özel-Tashenov et al., Nucl. Instr. and Meth. A 608 (2009) 287

TR0 TR1 TR2

3.8cm

3.8cm 24.5cm

11.3cm

13.2cm

7.6cm

Drift chambers

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24cm 14cm

120cm

90cm

Small DCBig DC

▶ Wire plane: xx’vv’uu’▶ Drift length: 2.5mm▶ Typical resolution(RMS): 0.30

mm

▶ Gas: Ar 70% + CO2 30%

▶ Insensitive in beam region by wrapping seinse wires with teflon

▶ Wire plane: XX’YY’U▶ Drift length: XY 4.5mm, U 9.0mm ▶ Typical resolution(RMS): XY 0.30 mm, U

0.40mm

▶ Gas: Ar 70% + CO2 30%

▶ Insesitive in beam region by connectiing sense and potential wires

ALADiN TOF wall

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▶ For -

▶ Plastic scintillators(96 bars)+ PMTs▶ Time resolution: ~ 200 ps ▶ Y position calculated by the

difference between top and bottom TDCs.

110cm

240cm

Big TOF wall (TFW)

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▶ For -

▶ X and Y layers (18 bars + 14 bars)

▶ Time resolution: ~ 200 ps (RMS)

150cm

188.5cm

TOF + wall

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▶ For and proton▶ Plastic scintillators (16 bars × 2

layers) with a hole for beam + PMTs

▶ Time resolution: 357±3 ps (FWHM)

▶ Energy resolution : 18 % (FWHM)

1m

96cm

hole : 7.5x6.5 cm2

Problems and improvement of Phase 0 Problems of Phase 0 experiment

Low efficiency of - detection

in ALADiN TOF wall Many events for scattering

particles

from TOF+ holding structure

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Phase 0.5 experiment▶ Study of heavier hypernuclei ▶ Beam: 20Ne at 2 A GeV with an intensity of

6 x105 /s ▶ Target : 12C with a thickness of 8 g/cm2

▶ Performed in March 2010

Improvement of setup in March

Movement of ALADiN TOF wall toward behind TOF+ wall- Cross-check positively charged particles with high energy deposition

Movement of Big DC closer to Big TOF - Avoid improper operation from much high multiplicity caused by 20Ne beam- Remove the background events from TOF+ holding structure

Phase 0.5 experiment

14 days in Mar. 2010

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▶ Beam: 20Ne at 2 A GeV with an intensity of 6 x105 /s to study light and heavier hypernuclei together ▶ Active Target : 12C with a thickness of 8 g/cm2

upstream

downstream

Experimental performance Phase 0 with 6Li beams

Multiplicity in TR1

QDC in TOF+

Phase 0.5 with 20Ne beams Multiplicity in TR1

QDC in TOF+

p

Li

CNe

O

p

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People working for HypHI Phase 0/0.5 GSI Helmholtz-University Young

Investigators Group VH-NG-239 S. Bianchin O. Borodina (Mainz Univ.) V. Bozkurt (Nigde Univ.) B.Göküzüm (Nigde Univ.) E. Kim (Seoul Nat. Univ) A. Le Fevre D. Nakajima (Tokyo Univ.) B. Özel C. Rappold (Strasbourg Univ.) T.R. Saito (Spokes person)

Mainz University P. Achenbach, J. Pochodzalla

GSI HP2 and Mainz University F. Maas, Y. Ma

GSI HP1 W. Trautmann

GSI EE department J. Hoffmann, K. Koch, N. Kurz, S. Minami, W.

Ott, S. Voltz

GSI Detector Lab. M. Träger, C. Schmidt

KEK T. Takahashi, Y. Sekimoto

KVI M. Kavatsyuk

Kyoto University T. Nagae

Osaka University S. Ajimura, A. Sakaguchi, K.Yoshida

Osaka Electro-Communication University T. Fukuda, Y. Mizoi

Tohoku University T. Koike, H.Tamura

Seoul National University H.Bhang, K. Tanida, M.Kim, C.Yoon, S.Kim

Nigde University S.Erturk, Z.S.Ketenci

Theoretical support T. Gaitanos (Giessen), E. Hiyama (RIKEN), D.

Lanskoy (Moscow), H. Lenske (Giessen), U. Mosel (Giessen)

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