christophe rappold for the hyphi collaboration · christophe rappold 1 for the hyphi collaboration...

Simulations for experiments on exotic hypernuclei

Christophe Rappold 1

for the HypHI collaboration

1Giessen University, Germany

1GSI - Darmstadt, Germany

HIC for FAIR Physics Day10 April 2015

Outline

Outline

Quick Introduction tohypernuclear physics

The HypHI project

Proposal to FRS andSuperFRS

For FRS

For SuperFRS

Summary & Perspectives

C. Rappold GSI-Giessen HypHI project 10/04/2015 2 / 30

Quick Introduction to hypernuclear physics

Outline


The HypHI project


For FRS

For SuperFRS




What and Why Hypernucleus ?

Classic example in Nuclear Physics:Neutron Star

I Core of neutron star → strangeness ?

I EoS of hyper-matter : Potential ofhyperons

Why not ?

Hyper

on

But, what is an hypernucleus ?

I Bound state of p,n andhyperon (Λ, Ξ, Σ) : A

YZ

And why ?

I No direct study ofhyperon-nucleon interaction



How to study Hypernucleus ?

Two distinct way

Missing mass spectroscopy

With secondary meson beams

I 50’ to 70’ : Emulsions ...

I Since the 70’ : Counterexperiments with fixedtarget.

I Since 2000 : also with e-beam on fixed target.

Invariant mass spectroscopy

With heavy ion :

I On fixed target :1988 Dubna, 2009-2010GSI

I Collider experiments :2009 STAR, 2011 ALICE



How to study Hypernucleus ?

Missing mass spectroscopy

Advantage :

I very precise spectroscopyof hypernuclei.

Disadvantage :

I Only from stable targetnuclei (production fromelementary process)

Invariant mass spectroscopy

Advantage :

I Lifetime measurements

I Production of exotichypernuclei

Disadvantage :

I Difficult experiments

I Lack of precise massresolution



Current hypernuclear chart

[O. Hashimoto, H. Tamura, Prog. Part. Nucl. Phys. 57 (2006) 564]


The HypHI project

Outline


The HypHI projectPhysics subjectsSetup - Overview


For FRS

For SuperFRS



The HypHI project

Physics subjects

Aims of the HypHI project started in 2006

To Use heavy ion and RI beam to study:I Hypernuclei toward the proton and neutron drip-lines:

I High isospin effects in YN interaction,

I Magnetic moments of hypernuclei.I Several other medium effects:

I Λ− Σ coupling in the nuclear matter.

I Exotic hypernuclei:I Decay of exotic hypernuclei,I Measurements of their lifetime & binding energy.

I Multistrangeness hypernuclei


The HypHI project

Physics subjects

Properties of the production mechanismprojectile nucleus

target nucleus

Hot dense region

remnant target

spectator projectile

Λ

I NN → ΛKN Energy threshold ∼ 1.6 GeV.I Beam energy > Eth: available at GSI (2 A GeV)I Coalescence of Λ or (π+,K+) reaction in spectator fragment.

⇒ same velocity than projectile: Lorentz BoostedI Effective lifetime longer:

I 200 ps → 600 ps (γ ∼ 3) at GSI: cτ ∼ 15 to 20 cm.=⇒ study Hypernuclei in flight

I Lifetime measurement via decay vertex reconstruction.


The HypHI project

Physics subjects

Several phases

Current knowledge:

Known Hypernuclei


The HypHI project

Physics subjects

Several phases

Ideal outcome of the HypHI project :

Known Hypernuclei

104/week

103/week


The HypHI project

Setup - Overview

Setup of Phase 0 experiment (October 2009)

0 m 1 m 2 m 3 m 4 m 5 m 6 m

TOF+ wall

TFW

ALADiN TOF wall

ALADiN dipole magnet

TR0TR1

TR2

BDCSDC

Li Beam

TOF-start

C Target

6

12

Z

XNegatively charged particle

Positively charged particle

3ΛH→ π−+3He4ΛH→ π−+4He5ΛHe→ π−+4He+p

Decay volume

Target: 12C, 8.84 g/cm2 ∼ 4 cm Length

Beam: 6Li at 2 AGeV, 3 106/s

3.5 days : ∼ 0.066 pb−1


The HypHI project

Setup - Overview

Hypernuclear spectroscopy from 6Li+12C @ 2 A GeV

mass (GeV)1.09 1.1 1.11 1.12 1.13 1.14 1.15

Co

un

ts / (

2.8

MeV

)

0

50

100

150

200

6.7 σ

Λ → p+π−

τ = 262+56−43 ± 45psmass (GeV)

2.97 2.98 2.99 3 3.01 3.02 3.03C

ou

nts

/ (

2.7

MeV

)

0

20

40

60

80

100

120

3ΛH → 3He+π−

4.7 σ

τ = 183+42−32 ± 37psmass (GeV)

3.9 3.92 3.94 3.96 3.98

Co

un

ts /

( 2

.8 M

eV

)

0

10

20

30

40

50

60

70

80

4ΛH → 4He+π−

4.9 σ

τ = 140+48−33 ± 35ps

Mass (GeV)2.04 2.06 2.08 2.1

Co

un

ts /

( 2

.8 M

eV

)

0

20

40

60

80

100

3Λn? → d+π−

3.7 σ

τ = 181+30−24 ± 25psMass (GeV)

2.98 3 3.02 3.04

Co

un

ts /

( 2

.8 M

eV

)

0

10

20

30

40

50

60

3Λn? → t+π−

5.2 σ

τ = 190+47−35 ± 36ps[ C. Rappold et al., Nucl. Phys. A. 913, 170 (2013) ]

[ C. Rappold et al., Phys. Rev. C (Rapid Comm.) 88, 041001 (2013) ]C. Rappold GSI-Giessen HypHI project 10/04/2015 13 / 30

The HypHI project

Setup - Overview

Reaction mechanism study

Production cross section & multiplicity :

CSΛ 1.7 ± 0.8 mb

3ΛH 3.9 ± 1.4 µb

4ΛH 3.1 ± 1.0 µb

3ΛH/

4ΛH 1.4 ± 0.8

3ΛH/Λ 2.6 ± 1.4 ×10−3

4ΛH/Λ 2.1 ± 1.1 ×10−3

y0

0.6 0.7 0.8 0.9 1 1.1 1.2 1.3

dN

/dy

/ (

0.0

2)

0

0.5

1

1.5

610×

3ΛH 〈y0〉 = 0.98

5.8 ± 2.1 × 10−6

y0

0.6 0.7 0.8 0.9 1 1.1 1.2 1.3

dN

/dy

/ (

0.0

3)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

610×

4ΛH 〈y0〉 = 1

4.6 ± 1.6 × 10−6

Pt (GeV/c)

0 0.2 0.4 0.6 0.8 1

dN

/dP

t /

(40

Me

V/c

)

810

710

610

510

3ΛH

Pt (GeV/c)

0 0.2 0.4 0.6 0.8 1

dN

/dP

t /

(40

Me

V/c

)

810

710

610

510

4ΛH

[C. Rappold et al., Under review PLB]


The HypHI project

Setup - Overview

Meanwhile the second experiment : Phase 0.5

I 20Ne + 12C @ 2AGeV

I 5 days of beam.

I Analysis on-going !

I good signals for Λ and 3ΛH


The HypHI project

Setup - Overview

Meanwhile the second experiment : Phase 0.5

Mass (GeV)

1.08 1.1 1.12 1.14 1.16 1.18

Co

un

t /

2.5

Me

V

0

100

200

300

Λ → p+π−

Prelim

inary

Mass (GeV)

2.96 2.98 3 3.02 3.04

Co

un

t /

3.1

Me

V

0

100

200

3ΛH → 3He+π−

Prelim

inary

I 20Ne + 12C @ 2AGeV

I 5 days of beam.

I Analysis on-going !

I good signals for Λ and 3ΛH


Proposal to FRS and SuperFRS

Outline


The HypHI project


Future plan

For FRS

For SuperFRS




Future plan

Prospects in Hypernuclear Physics for FRS/SuperFRS

Future of HypHI project : Exotic hypernuclei / strangeness cluster

Use heavy ion and RI beam to study @ FRS & SuperFRS :

I Hypernuclei toward the proton and neutron drip-lines withExotic beam ⇒ SuperFRS

I Λ− Σ coupling in the nuclear matter ⇒ SuperFRS

I Lifetime of exotic hypernuclei. ⇒ FRS / SuperFRS

I Most urgent : Confirmation of 3Λn ⇒ FRS



Future plan

Prospects in Hypernuclear Physics for FRS/SuperFRS

Why at FRS / Super FRS ?

I high momentum resolution for forward fragments :10−4δp/p optimal

I to be compared with previous experimental apparatus :∼ 10−2δp/p

I Exotic hypernuclei : Need RI beamI With high energy ∼ 2 AGeV (min 1.6AGeV)I With high intensity : small cross section (∼ µb)

I Optimizing each experiment to one decay / species

⇒ Only possible at GSI/FAIR and FRS / SuperFRS


For FRS

Outline


The HypHI project


For FRSTwo MagnetsSolenoid magnet

For SuperFRS



For FRS

Two Magnets

FRS setup: Physics case

I The most urgent : Confirmation of nnΛI Repeat the experiment 6Li + 12C (at 1.8 AGeV → 2 AGeV)I Looking for : nnΛ → d+π−

I at the same time (Benchmark) : 4ΛH → 4He + π−

I (same regidity d / 4He / 6Li)

I Can be the test case to demonstrate that hypernuclear studycan be performed within FRS, set as a fragment spectrometer.

I S2 as the location for the detector apparatus.


For FRS

Two Magnets

FRS setup: Physics case

I TA → S2 : primary beam transportI beam tuning such as: small angle to the hypernuclear

production target at S2

I S2 → S4 : fragment spectrometer for momentummeasurement for d and 4He

I Two options : two dipole magnets OR one solenoid magnet.


For FRS

Two Magnets

FRS setup : Two dipole magnet scenario

Possible setup at S2 of FRS with 6Li+12C @ 1.8 AGeV

Negatively charged particle (π−)

Beam

Decay volume

START + Target

Tracker stations(Fibers + DC)

π− detectors(DC + TOFPlus)

D-magnet / SKSPlus(KEK - Japan)

S2 Entrance Magnet

S2 Exit Magnet

π−

Fragments

X (cm)

Z (cm)


For FRS

Two Magnets

More Geometry


For FRS

Two Magnets

Characteristics

I Characteristic of the Sks magnet :I Gap (transversal) : 99 cm × 20 cmI Leff=1.075 mI Field : 1.034 TI Angle : 25 degree / Rho : 1.945 mI Weigth : 29 t

I Characteristic of the second magnet :I Gap Width : 25 cmI Gap Height : 20 cmI Gap Length : 75 cmI Field : 1.5 T

I Calculation on the realistic magneticfield done in KEK by magnet expert.


For FRS

Two Magnets

Characteristics

I Characteristic of the Sks magnet :I Gap (transversal) : 99 cm × 20 cmI Leff=1.075 mI Field : 1.034 TI Angle : 25 degree / Rho : 1.945 mI Weigth : 29 t

I Characteristic of the second magnet :I Gap Width : 25 cmI Gap Height : 20 cmI Gap Length : 75 cmI Field : 1.5 T

I Calculation on the realistic magneticfield done in KEK by magnet expert.

L (cm)

0 100 200 300 400

Fie

ld (

T)

1.5

1

0.5

0

0.5

1


For FRS

Two Magnets

Results of the systematic study

From MC simulations of fragments (6Li, 4He, 2H) :

How are the fragments with different field for the second dipolemagnet ?

0.9 Tm0.95 Tm

1 Tm1.05 Tm

1.1 Tm1.15 Tm

)°

An

gle

Px

/Pz (

1.5

1

0.5

0

0.5

1

1.5

0

100

200

300

400

500

H)2He, 4Li, 6

Angle before Quadripole (

0.9 Tm0.95 Tm

1 Tm1.05 Tm

1.1 Tm1.15 Tm

X P

os

itio

n (

cm

)

15

10

5

0

5

10

15

0

100

200

300

400

500

600

H)2He, 4Li, 6

Position After Quadripole (

cc


For FRS

Two Magnets


Combining Monte Carlo simulation of the setup & Mocadi

I ROOT Tree from the MC simulation → input to Mocadi.I The 4-vector of all deuteron at the entrance of the

quandripole.I propagation end of S2 → S4 done by Mocadi.

Momentum (GeV/c)

1.4 1.6 1.8 2 2.2 2.4

Eff

0

0.02

0.04

0.06

0.08

0.1

0.12

S3_eff

S3

Prelim

inary

Momentum (GeV/c)

1.4 1.6 1.8 2 2.2 2.4

Eff

0

0.005

0.01

0.015

0.02

0.025

0.03

S4_eff

S4

Prelim

inary


For FRS

Two Magnets


Rate estimation for d+π− in comparison with Phase 0 :

I Cross section at 1.8 AGeV instead of 2.0AGeVI 0.5 times less than in Phase 0

I Geometrical acceptance :I 0.6 times less than in Phase 0

I Data acquisition efficiency without the secondary vertextrigger :

I 10 times more than in Phase 0

I Total :I 3.0 times more yield than in Phase 0


For FRS

Two Magnets


Preliminary event reconstruction from MC simulations :From the fully detected tracks of d and π−

Mean 0.004242RMS 0.02192p0 648.8p1 0.003319p2 0.01373p3 73.6p4 0.008727p5 0.04064

dP/P

0.08 0.06 0.04 0.02 0 0.02 0.04 0.06 0.08

Co

un

ts

0

200

400

600

800

Mean 0.004242RMS 0.02192p0 648.8p1 0.003319p2 0.01373p3 73.6p4 0.008727p5 0.04064

mom1

π−

RMS : 1.5 %

Prelim

inary

Mean 0.0002902

RMS 0.01778p0 1.142e+04p1 0.0001187p2 0.01636p3 197.9p4 0.01301p5 0.06761

dP/P

0.06 0.04 0.02 0 0.02 0.04 0.06

Co

un

ts

0

5000

10000

Mean 0.0002902

RMS 0.01778p0 1.142e+04p1 0.0001187p2 0.01636p3 197.9p4 0.01301p5 0.06761

mom1fr

d

RMS: 1. %

Prelim

inary

cc


For FRS

Two Magnets


Monte Carlo simulation with 3Λn of 6Li+12C @ 1.8 AGeV

Preliminary event reconstruction from the MC simulation :→ From the fully detected tracks of d and π−

[C. Rappold, GSI Scientific Report 2014]

Mean 2.056

RMS 0.004815

Constant 2639

Mean 2.056

Sigma 0.003598

Invariant Mass (GeV)2.04 2.05 2.06 2.07 2.08 2.09

Co

un

ts

0

1000

2000

Mean 2.056

RMS 0.004815

Constant 2639

Mean 2.056

Sigma 0.003598

M2

RMS : 3.6 MeVPhase 0 : 4.7 MeV

Prelim

inary

Mean 2.059

RMS 0.000811

d+pi invariant mass (GeV)2.055 2.06 2.065 2.07 2.075

Co

un

ts

0

2000

4000

6000

Mean 2.059

RMS 0.000811

inv_mass

RMS : 0.8 MeV1% dp/p π−

0.1% dp/p d

Prelim

inary


For FRS

Solenoid magnet

FRS setup: Solenoid magnet scenario


For FRS

Solenoid magnet

Results of solenoid simulation

I π− momentum resolution within the solenoid+endcap.

)2

Momentum (GeV/cπ

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

p/p

∆

0

0.005

0.01

0.015

0.02


For FRS

Solenoid magnet

Results of solenoid simulation

I Transversal angle ∆Φ of the 6Li beam for 0.3 T and 0.7 T.

Mean 1.536

RMS 0.01966

(degree)φ∆

1.45 1.5 1.55 1.6

Co

un

t

0

200

400

600

800 Mean 1.536

RMS 0.01966

0.3 T

Mean 3.584

RMS 0.04628

(degree)φ∆

3.45 3.5 3.55 3.6 3.65 3.7

Co

un

t

0

100

200

300

400

500Mean 3.584

RMS 0.04628

0.7 T


For SuperFRS

Outline


The HypHI project


For FRS

For SuperFRSOpportunity withSuperFRS



For SuperFRS

Opportunity with SuperFRS

Opportunity with the SuperFRS : Hypernuclei @ SuperFRS

Feasibility study : proton-rich hypernuclei

I Experimental setup not yet fixed :Like with FRS or more dedicated setup.

I Study of the Rare Isotope beam production (Epax+Mocadi)

I Study of the hypernuclei production cross section

Primary beam + Production Target →Secondary beam + 2nd Target → Exotic Hypernuclei + X


For SuperFRS


SuperFRS : Physics case

Use of Rare Isotope beam for proton rich hypernuclei

Mocadi simulation for 9C beam :

I Production of secondary beam → 1010 / s primary beam

I Transport over the SuperFRS beamline

[C. Rappold, GSI Scientific Report 2013 p.176]

)2Target Thickness (g/cm

5 10 15 20 25 30

C B

ea

m I

nte

ns

ity

9

510

610

12C+12C

12C+9Be

13C+12C

13C+9Be

14N+12C

14N+9Be

15N+9Be

16O+9Be

17O+9Be


For SuperFRS



Use of Rare isotope Beam for proton rich hypernuclei

Theoretical cross section for the possible produced hypernuclei inthe collision 9C+12C at 2AGeV (DCM model)

[ A. Botvina et al. Phys. Rev. C. 86 (2012) 011601 ]

[C. Rappold, GSI Scientific Report 2013 p.176]

3ΛH

4ΛH

3ΛHe

4ΛHe

5ΛHe

6ΛHe

2 µb 1.2 µb 1.2 µb 3.4 µb 2.6 µb 1.4 µb

4ΛLi

5ΛLi

5ΛBe

6ΛBe

7ΛBe

8ΛBe

1.4 µb 1.2 µb 0.4 µb 1.6 µb 0.6 µb 0.8 µb

6ΛB

7ΛB

8ΛB

8ΛC

0.4 µb 0.2 µb 0.6 µb 0.2 µb


For SuperFRS



Monte Carlo Simulation :I Expected invariant mass of 8

ΛBe → 8B + π−, Γ(π−) ∼ 0.15I → MWD still possible for medium size hypernucleus :

([ T. Motoba et al. NPA 489 (1988) 683 ])

Mean 7.664

RMS 0.0008507

)2 ) Invariant Mass (GeV/c-πB + 8( 7.66 7.665 7.67

Cou

nts

/ 0.2

MeV

0

5000

10000

15000Mean 7.664

RMS 0.0008507

Prelim

inary

I Mass resolution 0.850 MeV (FWHM 0.79 MeV)I with 1% dp/p for π− and 0.1% dp/p for 8B



Outline


The HypHI project


For FRS

For SuperFRS




Summary

I The Phase 0 of the project was completed in October 2009and March 2010

I Demonstrated the feasibility of HypHI by observing the MWDof Λ, 3

ΛH,4ΛH & Evidence of 3

Λn existenceI Open geometry experiment feasible : inclusive measurements.I Can study hypernuclear structure.I Can use hypernuclei as probe for nuclear reaction study.

I hypernuclear study @ FRS and SuperFRSI More precise hypernuclear spectroscopy.I FRS / SuperFRS as a dedicated fragment spectrometer.I Exclusive measurements : hypernuclear structure only.



Summary

I FRS and SuperFRS as high resolution forward spectrometerfor hypernuclear study

I in near future at FRS :⇒ Possibility to confirm the existence of 3

Λn via d+π− :6Li+12C @ 1.8 ∼ 2 AGeV

I in future at SuperFRS : First simulation for studyingproton-rich hypernuclei⇒ Example of hypernuclei 8

ΛBe with a cross section of 0.8 µbI Unique opportunity with SuperFRS for exotic hypernuclei &

MEMO (Metastable exotic multi-hypernuclear object)


christophe rappold for the hyphi collaboration · christophe rappold 1 for the hyphi collaboration...

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