HHIQCD Workshop 2015 at YITP

Search for η' mesic nuclei with (p,d) reaction at GSI!
!
Yoshiki K. Tanaka! (Univ. of Tokyo)
for the η-PRiME collaboration!
Y. Ayyad, J. Benlliure, K.-T. Brinkmann, S. Friedrich, H. Fujioka, H. Geissel, !
J. Gellanki, C. Guo, E. Gutz, E. Haettner, M. N. Harakeh, R. S. Hayano, !
Y. Higashi, S. Hirenzaki, C. Hornung, Y. Igarashi, N. Ikeno, K. Itahashi, !
M. Iwasaki, D. Jido, N. Kalantar-Nayestanaki, R. Kanungo, R. Knoebel, !
N. Kurz, V. Metag, I. Mukha, T. Nagae, H. Nagahiro, M. Nanova, T. Nishi,!
H. J. Ong, S. Pietri, A. Prochazka, C. Rappold, M. P. Reiter, J.L. Rodríguez-Sánchez !
C. Scheidenberger, H. Simon, B. Sitar, P. Strmen, B. Sun, K. Suzuki, !
I. Szarka, M. Takechi, Y. K. Tanaka, I. Tanihata, S. Terashima, Y. N. Watanabe, !
H. Weick, E. Widmann, J. Winfield, X. Xu, H. Yamakami, J. Zhao !
Osaka University, Universidade de Santiago de Compostela, Universitaet Giessen, !
Kyoto University, GSI, University of Groningen, Beihang University, !
The University of Tokyo, Nara Women's University, KEK, RIKEN, !
Tokyo Metropolitan University, Saint Mary’s University, !
Technische Universitaet Darmstadt, Comenius University Bratislava, !
Stefan Meyer Institut, Niigata University

η′ meson
Massη′! meson!

M=958 MeV/c2	

Γ=0.198 MeV	

Pseudoscalar meson ( Jπ=0-)	!

Decay mode 	

π+π-η(43%),	

ρ0γ(29%),	π0π0η(22%) 	

2

η′ meson0UA(1) anomaly⇥, K, 8 , 0K⇥, K, 8masslessmq = ms = 0mq = ms = 0mq = ms = 0q̄q⇥ = 0⇥q̄q⇤ = 0⇥q̄q⇤ = 0

ChS manifest

ChS broken dynamically

ChS broken dynamicallyand explicitly!
3H.Nagahiro  et  al.,PRC  87  (2013)  045201.

η′ meson
UA(1) anomaly effect on η′ mass
- KMT interaction in NJL model- related to the strength of	chiral condensate <qq>!

by Hirenzaki
4

Kobayashi-Maskawa-’t Hooft 	

6-point vertex 	

Kobayashi, Maskawa, PTP44(70)1422	

‘t Hooft, PRD14(76)3432. 	

T. Kunihiro, Phys. Lett. B219(89)363.	

Klimt, Lutz,Vogl, Weise, NPA516(90)429.

η′ meson in medium- Chiral condensate |<qq>|	

reduced by ~30% at ρ0.

partial restoration of chiral symmetry

K. Suzuki et al., !
-30 % PRL92(04)072302

ρ0W. Weise, !
NPA553(93)59.

5

η′ meson in medium- Chiral condensate |<qq>|	

reduced by ~30% at ρ0.

partial restoration of chiral symmetry- Mass reduction expected	

e.g., NJL model calculation 	→ 150 MeV/c2 mass reduction

K. Suzuki et al., !
-30 % PRL92(04)072302

ρ0W. Weise, !
NPA553(93)59.
P.Costa  et  al.,PLB560,  (2003)  171.  
H.Nagahiro  et  al.,PRC  74,  (2006)  045203.

6

in-medium mass and widthρ(r)η′ nucleus optical potential : Vη’ = (V0+iW0)
ρ0
V0 = Δm(ρ0), W0 = −Γ(ρ0) / 2- model predictions	Δm(ρ0) ~ -150 MeV (NJL model)	 → strong attraction ?
~ - 80 MeV (linear σ model)	

S. Sakai, D. Jido, PRC 88, 064906 (2013)	

~ - 37 MeV (QMC model) for θηη’=-20°	

S.D. Bass, A.W. Thomas, PLB 634, 368 (2006)- CBELSA/TAPS 	M. Nanova et al., Phys. Lett. B 727 (2013) 417 !
V0 = -37 ±10(stat) ±10(syst) MeV
M. Nanova et al., PLB710, 600(2012)Γ (ρ0) = 15 - 25 MeV, for Pη′, average =1.05GeV/c- relatively small η′-proton scattering length
E. Czerwiński et al., PRL 113, 062004 (2014)
Re{aη’p}= 0 ± 0.43 fm

7

in-medium mass and widthρ(r)η′ nucleus optical potential : Vη’ = (V0+iW0)
ρ0
V0 = Δm(ρ0), W0 = −Γ(ρ0) / 2- model predictions	Δm(ρ0) ~ -150 MeV (NJL model)	 → strong attraction ?
~ - 80 MeV (linear σ model)	

S. Sakai, D. Jido, PRC 88, 064906 (2013)	

~ - 37 MeV (QMC model) for θηη’=-20°	

S.D. Bass, A.W. Thomas, PLB 634, 368 (2006)- CBELSA/TAPS 	M. Nanova et al., Phys. Lett. B 727 (2013) 417 !
V0 = -37 ±10(stat) ±10(syst) MeV
M. Nanova et al., PLB710, 600(2012)Γ (ρ0) = 15 - 25 MeV, for Pη′, average =1.05GeV/c- relatively small η′-proton scattering length
E. Czerwiński et al., PRL 113, 062004 (2014)
Re{aη’p}= 0 ± 0.43 fm!

|W0| < possible potential depth |V0| 	

→ possibility for observing η′ meson-nucleus	

bound states (η′mesic nuclei) experimentally

Missing mass spectroscopy of (p,d) reaction!

2.5 GeV proton beam	

momentum measurement	

by Fragment Separator
missing-mass spectrum

Targetη′ mesic nuclei

K. Itahashi et al., 	PTP 128,601(2012)

1stStep:
Inclusivemeasurementof(p,d)
reaction
atGSI	!
- unbiased analysis without assumption on decay process 	- poor S/N ratio due to BG processes (e.g., multi-pion production)

9Missing mass spectroscopy of (p,d) reaction!

2.5 GeV proton beam	

momentum measurement	

by Fragment Separator
missing-mass spectrum

Targetη′ mesic nuclei

K. Itahashi et al., 	PTP 128,601(2012)

1stStep:
Inclusivemeasurementof(p,d)
reaction
atGSI	!
- unbiased analysis without assumption on decay process 	- poor S/N ratio due to BG processes (e.g., multi-pion production)
High-statistics measurement is essential	

using high-intensity beam
+ thick target
10

Theoretical cross section of 12C(p,d)11C×η′η′ nucleus optical potential :ρ(r)Vη’ = (V0+iW0)
ρ0- Green’s function method 	

- proton energy 2.5 GeV,	mom. transfer ~ 400 MeV/c

V0 = Δm(ρ0), W0 = −Γ(ρ0) / 2!
11H.Nagahiro  et  al.,PRC  87  (2013)  045201.

Theoretical cross section of 12C(p,d)11C×η′η′ nucleus optical potential :ρ(r)Vη’ = (V0+iW0)
ρ0- Green’s function method 	

- proton energy 2.5 GeV,	mom. transfer ~ 400 MeV/c

V0 = Δm(ρ0), W0 = −Γ(ρ0) / 2!
12H.Nagahiro  et  al.,PRC  87  (2013)  045201.

Simulation of inclusive measurement(V , W0)=−(200, 5) MeV(V , W0)=−(150, 5) MeV

0275000counts/2MeV0ηʼ’  production

275

270
270000265
265000285285000

background    (e.g.,p+N→d+πʼ’s)(V , W0)=−(200, 10) MeV(V , W0)=−(150, 10) MeV

Sim0

280
280000275275000270270000(V , W0)=−(100, 10) MeV

0265

265000260
260000285285000!

(V , W0)=−(100, 5) MeV

0260
260000(V0 = Δm(ρ0), W0 = −Γ(ρ0) / 2)

(V , W0)=−(200, 20) MeVula(V , W0)=−(150, 20) MeV000tion(V , W0)=−(100, 20) MeV
0280
280000275275000counts/2MeV

counts/2MeV

S/N ratio ~ O(1/100) 	

at most×103

280
280000counts/2MeV

V0, W0 :	

real, imaginary part 	of optical potential
ρ(r)Vη’ = (V0+iW0)
ρ0counts/2MeV

K. Itahashi et al., 	PTP 128,601(2012)

285000counts/2MeV

Simulated spectra ofinclusive measurement	

assuming 4.5 day DAQ

285

270
270000265
265000260
260000255
255000-40-20020-40-20020
Excitation Energy [MeV]
Excitation Energy [MeV]-40-20020-40-20020
Excitation Energy [MeV]
Excitation Energy [MeV]-40-20020-40-20020
Excitation Energy [MeV]
Excitation Energy [MeV]First experiment at GSI (2014 Aug.)in a framework of the Super-FRS collaboration for FAIRGSI facilities
Ion sources

CALI
UN

Ion source
12C target

momentum 	

analysis

2.5 GeV proton
15Experimental setup at FRS
p (Tp = 2.5 GeV, Ip ~ 4 ×1010/spill)
12C target (4 g/cm2)

signald (Pd = 2.7-2.9 GeV/c)	

momentum	~ 4 k/spill at S4, βd ~ 0.83 measurement

18machromaticS2MWDC×2
S4SC ACdispersive(Scintillator	(SC)3.6cm/%)

Fragment Separator (FRS)
16Aerogel 	

Cherenkov (AC)Experimental setup at FRS
p (Tp = 2.5 GeV, Ip ~ 4 ×1010/spill)background12p′~ 800 k/spill at S4, βp ~ 0.95
C target (4 g/cm2)

signald (Pd = 2.7-2.9 GeV/c)	

momentum	~ 4 k/spill at S4, βd ~ 0.83 measurement

18m

achr
oma
ticS2

MWDC×2S4SC ACdispersive(Scintillator	(SC)3.6cm/%)

Fragment Separator (FRS)
17Aerogel 	

Cherenkov (AC)Particle Identification
TOF S2-S4

S2-deuteronS4-deuteron104800k/spill

CountsCounts

10ns
10ns/grid

S2-S4 TOF (unbiased)
p/d ratio ~ 200 / 1dental)-proton

10220ns

deuteron

10S2-proton
S4-proton103

preliminary

proton→	timeS4-proton

18

1-5400-5200-5000-4800 -4600 -4400 -4200
TOF (S2-S4) + offset [/25ps]

-4000

-3800

TOF (S2-S4) + offset [/25ps]-3600

Particle Identification
TOF S2-S4

S2-deuteronS4-deuteron104

800k/spill

CountsCounts

10ns
10ns/grid

S2-S4 TOF (unbiased)p/d ratio ~ 200 / 1

S4-proton

2deuteron1→	

time-5400-5200-5000-4800 -4600 -4400 -4200
TOF (S2-S4) + offset [/25ps]

with hardware TOF trigger
p/d ratio ~ 1 / 1-4000

-3800

-3600

TOF+S2-S4
TOF (S2-S4)
offset [/25ps]
3000

preliminary

2500

2000

CountsCountsdental)-proton

1020ns10

S2-proton
S4-proton

103preliminary

protonaccidental 	multi-hit	(proton)

1500

1000

deuteron

500

019-5400-5200-5000-4800 -4600 -4400 -4200
TOF (S2-S4) + offset [/25ps]-4000-3800

TOF (S2-S4) + offset [/25ps]-3600

Particle Identification
TOF S2-S4
104800k/spill

CountsCounts

10ns
10ns/grid

S2-S4 TOF (unbiased)
p/d ratio ~ 200 / 1

S2-deuteronS4-deuteron

10220ns

deuteron

10S2-proton
S4-proton

1→	

timedental)-proton

-5400

-5200

with hardware TOF trigger
p/d ratio ~ 1 / 1-4800 -4600 -4400 -4200
TOF (S2-S4) + offset [/25ps]

-4000

-3800

-3600

TOF+S2-S4
TOF (S2-S4)
offset [/25ps]

preliminary

2500

2000

99.5 % of BG protons were
rejected by TOF trigger	

without using AerogelČerenkov detector

-5000

3000

CountsCounts

S4-proton103

preliminary

protonaccidental 	multi-hit	(proton)

1500

1000

deuteron500020-5400-5200-5000-4800 -4600 -4400 -4200
TOF (S2-S4) + offset [/25ps]

-4000

-3800

TOF (S2-S4) + offset [/25ps]-3600

Particle Identification
Further rejection of the accidental multi-proton in offline analysis- Single pulse selection by waveform analysis 	- Cut condition for corrected TOF (S2-S4)	

→ proton contamination is sufficiently small
Examples of waveform of SC at S2Entries

ADC valuev1742vt_cut_h1_2 03:04:20 2014-10-07 Analysis/Histograms/Raw data/V1742VT_CUT_H1/v1742vt_cut_h1_2

v1742vt_cut_h1_2__2

Mean
RMS

136
65.54
37.84

Underflow
Overflow
Integral
Skewness0
2.17e+04
4.572e+05-0.03785

4000

TOF (S2-S4)

tof_2h_41

3500
3000

ba

RMS

116541220486
-4223
-4241
10.73
106.6

preliminary5000

deuteron-like

2500

Entries
Entries
Mean
Mean
RMS

2000

4000

1000
500
00

20

40

60

80

100

120
time [ns]v1742vt_cut_p_h1_2__1

EntriesMean
RMS

ADC valuev1742vt_cut_p_h1_2 03:07:20 2014-10-07 Analysis/Histograms/Raw data/V1742VT_CUT_P_H1/v1742vt_cut_p_h1_2

136
65.35
38.31

Underflow
Overflow

02.156e+04

Integral
Skewness

4.423e+05-0.02896

4000
3500

Counts [a.u.]

1500

deuteron

3000

accidental 	multi-hit	(proton)

2000

3000
2500

multi-proton-like

2000
1500

1000

σ~160ps0-5000

1000

-4800

-4600

-4400

-4200

-4000

-3800

TOF (S2-S4) + offset [/25ps]

50000

slewing effect and 	(δ,a)-dependence corrected,
height is ×1/4 scaled

20

40

60

80

100

120
time [ns]21-3600

MWDC Analysis-! MWDC(XX’XX’UU’VV’)×2 were used.	

- Tracking : 	

2 fitting for 2 MWDCs	drifttime(measured)→driftlength→χ!
- Iterative analysis for calibration :	temporarydrift
length→tracking→
evaluate
andupdate
drift
length	!
- Time dependence of relation between drift time and drift length	

Drift length calibration

3Drift length drift[mm]
length [mm]20.8Time dependence of drift time to	drift length relation
for drift time=1555 (TDC channel)

0.75

10~1day

0.7

0.65-1-20.60.55
78time[day]Aug. 86

Aug. 75

Aug. 64

Aug. 5223

Aug. 4

Measured drift time [TDC channel]

0.52

Aug. 3-314001420 1440 14601480 1500 15201540 1560 15801600
Drift Time [channel]

Aug. 2	

0:00

Evaluated
lengthDriftdrift
Length[mm] [mm]!
!

Spectrometer Calibrationp (Tp = 1.6 GeV )D(p,d)p elastic scattering 	

for spectrometer calibration

CD2 target (1 g/cm )2d (Pd = 2.82 GeV/c)	

18m

achr
omaticS2

momentum	

measurement
MWDC×2S4SC ACdispersive(Scintillator	

(SC)3.6cm/%)

Fragment Separator (FRS)
23

Aerogel 	Cherenkov (AC)Spectrometer Calibration
X (horizontal position) - X′(angle) by MWDC
-1%

30

X-X’ at MWDC

0%+1%

FRS scaling 	

by -2%
20+2%

10[mrad]X′X’ [mrad]preliminary

0-10-20-30-150-100-500
X [mm]

50100

150X [mm]- the whole system is working well	- Ion-optical information (focus, dispersion, higher-order aberration)	

24→ (x|a),(x|δ),(x|aδ),(x|aa), ….

Spectrometer Calibration
Focal plane position (online, ion-optics roughly corrected)
aCounts4cor_x6000

preliminary-1% 0%

5000

FRS scaling 	

by -2%
4000

1%

3000

2%

2000

1000

0-100-50

050100X at Focal Plane [mm]σX =! 2.7 mm (CD2 calibration run)	

- energy loss and straggling calculation	- spectrometer momentum resolution	

- beam momentum spread

Expected resolution : σmissing mass ~ 2 MeV/c2 (production run)	

25

Run Summary
Production run (~ 5 days)	

- C(p,d) reaction at Tp=2.5 GeV 	

with ~ 4 ×1010/spill proton beam and 4 g/cm2 C target 	- scaling FRS Bρ from -2% to 2% → -90 MeV < Eex-E0 < +40 MeV covered 	- (5−10)×106 deuterons/setting were accumulated	- spectrometer calibration every 6 hours	

!
!

Reference run (~ 0.5 day)- production setting with CD2 target, for D(p,d) spectrum	

- for understanding background processes (e.g., p+N→d+π’s)	

- scaling FRS Bρ from -2% to 2%	Region in excitation energy

FRS scaling-2%0%+2%-100

26-50Eex - E0 [MeV]

050100Future plan at FAIR

FAIR facilities
Facility for Antiproton and Ion Research (FAIR)
p-LINAC

SIS-100 / SIS-300

SIS-18UNILACCBMRare Isotope	Production Target

HESR
PANDA

GSI

Super-FRS
Antiproton	

Production Target

Plasma Physics
Atomic Physics

RESR/	CR

FLAIR
NESR

28

50 m

Future plan at FAIR!

1st Step : Inclusive measurement of (p,d) reaction with FRS at GSI	!
!

2nd Step : - Inclusive measurement with higher intensity beam at FAIR	- Semi-exclusive measurement of (p,dp) with Super-FRS at FAIR
missing-massmeasurement w/ S-FRS

Targetη′ mesic nuclei

29

Future plan at FAIR!

1st Step : Inclusive measurement of (p,d) reaction with FRS at GSI	!
!

2nd Step : - Inclusive measurement with higher intensity beam at FAIR	- Semi-exclusive measurement of (p,dp) with Super-FRS at FAIR
missing-massmeasurement w/ S-FRSNTarget

decayof η’ mesic nuclei :!
- η′N → ηN or πN	

- η′NN → NNNη′ mesic nuclei

Tagging proton in	coincidence with deuteron→ S/N ratio can be improved30

Tagging decay proton
signalη′ mesic nuclei

backgroundmulti-π production

2 nucleon absorption

1 nucleon absorption
×102
800

sampling calorimeter(conceptual design)count [a.u.]

700600

proton 	beam500400300
200
100000.2

0.4

0.60.81.01.2

proton momentum [GeV/c] 31

deuteronproton

Microscopic transport model calculation

An analysis of the 12C(p,d) reaction
at eta'(958) meson production region
by microscopic transport model (JAM)

1!!	  JAM	  was	  developed	  by	  	  	  	  	  	  	  	  	  	  	  	  	  	  Y.	  Nara,	  N.	  Otuka,	  A.	  Ohnishi,	  K.	  Niita,S.	  Chiba,	  	  Y. Higashi (Nara WU)!
Hadrons in Nuclear medium IIWorkshop at J-PARC	  	  	  	  	  	  	  	  	  	  	  	  Phys.	  Rev.	  C61,	  024901	  (2000).	  

32

Microscopic transport model calculation!

JAM simulation!

Y. Higashi, !
Hadrons in Nuclear medium II
Workshop at J-PARC

3.Discussion : Comparisonof Signal
withBackground
Background
events: (mainlydueto multi
S production)(obtained by independent simulations)

Considered range of the missing mass : K’  threshold

60MeV.

By JAM, the distributions of emitted
particles from No-K’-Processes can beinvestigated.
The S/N ratio is improved by the factor of 100.
33

410

Microscopic transport model calculation!

JAM simulation!

Y. Higashi, !
Hadrons in Nuclear medium II
Workshop at J-PARC

3.Discussion: Comparisonof Signal
withBackground
Simulation
results:
ComparisonofSignal
withSBackground
Background
events:(mainlydueto multiproduction)(obtainedby independentsimulations)
Emittedparticles from K’  absorption.

• Signal• Background

Emitted particles from No-K’-processes.

Background(calculation by JAM)

Proton momentum	

vs Angle (cosθ)high momentum proton	

at backward angle 	→ clean region

SignalExpected momentum distribution of proton
just after K’  absorption  in  nucleus

two–nucleon
absorption

Considered range of the missing mass : K’  threshold

60MeV.

By JAM, the distributions of emitted
fromNo-K’-Processes
can beNumberparticles
of protons withlarge
momentum at backward
directions: small!
investigated.
The S/N ratio could be improved by using the protons from two-nucleon
absorption of K’!  (proton  with  large  momentum  at backward directions
6 4
The S/Nratio is improved by the factor of 100.
seems
important.)
3410Microscopic transport model calculation!

JAM simulation!

Y. Higashi, !
Hadrons in Nuclear medium II
Workshop at J-PARC

3.Discussionof Signal
BackgroundK’  Processes::Comparison
Emitted particles
fromwith
K’  - Processes
by independentsimulations)Here,(obtainedwe consider
two-Nucleon absorptionof K’
Proton has

The S/N ratio is improved by the factor of 100.
35510

Microscopic transport model calculation!

JAM simulation!

Y. Higashi, !
Hadrons in Nuclear medium II
Workshop at J-PARC

3.Discussion : Comparison of Signal with Background(obtained by independent simulations)Proton momentum	vs Angle (cosθ)S/N ratio can be 	

improved by ~100

The S/N ratio is improved by the factor of 100.
3610Summary● Missing-mass spectroscopy of η′ mesic nuclei with (p,d) reaction 	

is performed for studying in-medium properties of η′ meson 	!

● In case of large mass reduction (~100MeV) and narrow decay width 	(~20MeV), η′ mesic nuclei may be observed in missing-mass spectrum.	

!

● The first inclusive measurement using FRS at GSI has been performed. 	

Data with good statistics and quality were obtained. 	

Analysis of missing-mass spectra is currently underway.	

!

● At FAIR, we plan semi-exclusive measurement of (p,dp) reaction 	

as well as better-statistics inclusive measurement. Tagging decay 	

protons can improve S/N ratio. R&D is presently on-going.	

37