Systematic studies of deeply-bound pionic atoms at the ... · the spherical 208pb nucleus. The...

Hayano, MESON 2014, Kraków

Systematic studies of deeply-bound pionic atoms

at the RIKEN RIBF facility

Ryugo S. Hayano (Tokyo) for the pionic atom factory project


The team (now busy at RIBF)

G.P.A. Berg, M. Dozono, H. Fujioka, N. Fukunishi, H. Geissel, E. Haettner, R.S. Hayano,  S. Hirenzaki, H. Horii, N. Ikeno, N. Inabe, K. Itahashi, M. Iwasaki, D. Kameda, N.Kobayashi,  T. Kubo, H. Matsubara, S. Michimasa, K. Miki, G. Mishima, H. Miya, H. Nagahiro, M. Niikura,  T. Nishi, S. Noji, S. Ota, H. Outa, H. Suzuki, K. Suzuki, M. Takaki, H. Takeda, Y. K. Tanaka,  T. Uesaka, Y.N. Watanabe, H. Weick, H. Yamakami, K. Yoshida  

!University of Notre Dame RIKEN Kyoto University GSI The University of Tokyo Nara Women's University National Institute of Radiological Sciences CNS, University of Tokyo RCNP, Osaka University National Superconducting Cyclotron Laboratory, Michigan State University Stefan Meyer Institut fuer subatomare Physik

0 50 m

SRC

IRC

fRC

AVF

RRC

RIPS

RILAC

BigRIPS


why? - chiral condensate

Already discussed by S. Hirenzaki


Deeply bound pionic atoms

π−

Quantum bound system of meson-nucleus

N. Ikeno et al., PTP126(2011)483.

radius [fm]

Nuclear density

pion density

Overlap

Probes ~60% of ρ0


Deeply bound pionic atoms

300 MeV

Normal NuclearDensity

ρT

||–-(250 MeV)3

-35%

5ρ0

Quantitative evaluation of chiral order parameter


Binding energy → 〈qq〉

NormalNucleus

|r,T|

5r0T

300 MeV

TemperatureDensity

r

pionic atom 1s energy

b0(ρn + ρp) + b1(ρn − ρp)

b1 ∝mπ

f2π(ρ)

Tomozawa-Weinberg

f2π(ρ)m2

π ≈ −mq < q̄q >ρGell-Mann Oakes Renner


GSI experiment (pionic Pb, Sn)

successfully completed some 10 years ago


Level scheme

1s

Pio

n D

en

sity [

1/f

m]

r [fm]R0

0.0

0.05

0.10

0.15

0 10 20 30 40

0

5

10

BindingEnergy(MeV)

�- - 208Pb

1s

1s

2s

2s3s3s4s5s

2p

3p

4p5p

3d

4d5d

Optical Potential

Finite - Size Coulomb

Absorption width

Shift

Width

s-wave real

p-wave real

Imaginary

effect of the strong interaction


Pionic X-rays

Strong Interactionπ absorption

Invisible

“deep” states invisible to X-rays


“last orbit”

Volume 162B, number 1,2,3

I , _ _ . _ _ , I

g o

i0 a_

PHYSICS LETTERS 7 November 1985

b

F

2~0 40~ 6 ~ 8 ~ t~0~ 1 2 ~ 1400

Energy (keV)

Fig, 1. The X-ray spectrum of pionic 2°apb after selecting the prompt part of the time distribution. The spectrum is essentially free from neutron-induced "r-ray background, as a consequence of the time window in the time-of-flight spectrum. The main nX- rays have been indicated in the figure. Most other T-rays are nuclear transitions in T1 isotopes occurring after pion capture in the 208 Pb nucleus.

distortion could not be correctly dealt with. The pres-

ent investigation avoids this complication by studying

the spherical 208pb nucleus.

The experiment was performed at the pion beam

at SIN, Switzerland. The pion beam was tuned for

100 MeV/c particles. Approximately 106 rr-[s were

stopped in a 208pb target [15 g of PbO and 20 g of

Pb(NO3)2 enriched to 99% in mass 208]. The experi-

mental set-up and measuring technique, including a

BGO Compton suppression spectrometer, were the

same as described earlier [ 1,11 ], measuring energy and

time-of-flight of every event on magnetic tape. This

method takes care of any difference in time resolution

as a function of ' /-ray energy.

In fig. 1 we show the prompt part of the pionic X-

ray spectrum up to 1600 keV. This Compton sup-

pressed spectrum is essentially free from delayed neu-

tron-induced T-ray background. Figs. 2a and 2b dis-

play details of the same spectrum also on a logarith-

mic scale, regarding the 5g ~ 4fand the 4f-~ 3d tran-

sitions, respectively. The solid lines represent fits to

the data points. Contrary to the analysis of ref. [2],

we include in our fits all the transitions in the energy

regions of interest. This enables us to reduce consider-

ably systematic errors in the fits, down to 1.4 keV in

the 4 f ~ 3d transition as compared to 4.6 keV in ref.

[2]. Our systematic error is mainly caused by the un-

certainty in the fitted background (see below). In table 1 the results of the pionic X-ray intensities

and transition energies are presented. The experimen-

tal energies and intensities are in rather good agree-

ment with the calculated values, obtained by using the

pionic X-ray cascade code STARKEF, which uses the

observed transition energies and level widths as input.

In table 2 we present the strong interaction shifts

and widths of the 4f and 3d levels, determined as in

earlier work [6,11], from the X-ray spectrum using a

lorentzian shape folded with the response function of

the Ge-detector. This instrumental response function

is of vital importance [1,11 ] in extracting the lorentz-

82

Volume 162B, number 1,2,3 PHYSICS LETTERS 7 November 1985

4

I0--

w

§ o

,0 ~_

' ' ' ' i ' I i I l I I L I i , , ¢ i , , i * I , , t i

a ~ 5 9 - 4 f '

.,,.,,j ' ' T W ~

' f , i , I i I i i i i f i i i i i i i T I I I I ] I I I

5 7 0 5 6 0 ~ 5 9 0

E n e r g y ( k e V )

Z = = 1 . 0 2

1 1 1 1 1 1 1 1 1 1 i l l l l l l l l i i l l l t I I E I t l * 1 I I I I I I I I t I I I I 1 [ 1 1 1 1 1 1

i o o o -

8 0 0

ooi ' 1 ' ' ' ' ' ' ' 1 ' ' . . . . . ' ' 1 ' . . . . . I . . . . ' . . . . I ' ' ' ' ' ' 1 . . . . .

1200 1225 1 2 5 0 1 2 7 5 1 3 0 0 1 3 2 5

E n e r g y ( k e V )

Fig 2. (a), (b) These figures display part of the prompt X-ray 2°spb spectrum, showing the energy regions of the 5g -~ 4f and

4 f ~ 3d ~rX-ray transitions, respectively. The solid lines represent the fits to the data points. The fitted backgrounds also shown in

the f'~,ures were obtained by fitting large energy intervals below and above the regions of interest. The various -f-rays also included

in the fitting procedure have all been identified as transitions from T1 isotopes in the mass region A = 200-205.

83

7i→6h

6h→5g

5g→4f

6g→4f

7g→4f

8g→4f

4f→3d

Pionic Pb, 4f→3d (“last orbit”)

1sP

ion D

ensity [

1/fm

]

r [fm]R0

0.0

0.05

0.10

0.15

0 10 20 30 40

0

5

10

BindingEnergy(MeV)

�- - 208Pb

1s

1s

2s

2s3s3s4s5s

2p

3p

4p5p

3d

4d5d

Optical Potential

Finite - Size Coulomb

Absorption width


(d,3He) reaction

Incident energy [MeV/u]100 150 200 250 300 350 400

Mom

entu

m tr

ansf

er [M

eV/c

]

0

50

100

150

200

250

300

350

Qvalue = -140!Qvalue = -135

Missing mass spectroscopy

n -

124Sn

d 3He

123Sn -

np-

p pp n

124Sn(d,3He)

n

neutronhole

recoilless condition@250 MeV/u


SETUP

d

3He

FRS

250


Pionic Sn at GSI

1s

Calibration

115Sn

119Sn

123Sn

NNDC,BNL

Nuclear chart

K. Suzuki et al., PRL92 072302 (2004)


Pionic atoms and chiral condensate

~ 10 % errorIsovector b1

K. Suzuki et al., PRL92(04)072302.

−0.14 −0.13 −0.12 −0.11 −0.10 −0.09

Pb-1s

Sn-1s In-vacuum b1In-medium b1*

b1

Pionic hydrogen X-ray spectroscopy at PSI


why further measurements?


why further measurements?

① Experimental error (ΔBE1s) ② Errors in other params. (b0, ρn, ReB0…)

① → Higher statistics, better resolution ② → systematic study (disentangle the QCD effects from mundane  nuclear effects)

b1 precision limited by

Improvements by


Binding Energy precision

・σ(stat) → higher statistics ・σ(sys) → by 1s & 2s measurement

Experimental errors

*N. Ikeno et al., Eur. Phys. J. A 47, 161 (2011)

2s

1s

How to improve


piAF @ RIBF - what can be improved?


b1 with better precision - longer lever arm

Vs = b0� + b1(�n � �p) + B0�2.π-A s-wave interaction → 〈qq〉


b1 with better precision - 2D coverage

Vs = b0� + b1(�n � �p) + B0�2.π-A s-wave interaction → 〈qq〉


GSI and RIBF

0 50 m

SRC

IRC

fRC

AVF

RRC

RIPS

RILAC

BigRIPS

GSI facilities

　　　　

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　

RIBF

GSI RIBFintensity ~10 ~10 ×50

Target 20 mg/cm 10 mg/cm ×0.5angular

acceptance ~10 mrad 40 / 60 mrad ×20

Δp 0.03% 0.1% ×3

resolution (FWHM) 400 keV 200~300 keV factor 1.3 ~ 2

using dispersion matching

✘

11 12

2 2


pilot experiment @ RIBF


The pilot experiment @ RIBF

NNDC,BNL

First Experiment

Nuclear chart


Experimental setup

d beam 100pnA, 250 MeV/u

F5

F7

Target

SRC

ScintillatorMWDC x 2

Scintillator

TOF measurementΔE measurement

3He 102 /s

3He Tracking

BigRIPS

Dispersive focal plane


122Sn(d,3He) (15 hours) - why 3 peaks?

He [mm]3Horizontal position of -100 -50 0 50 100

Cou

nts/

0.5

mm

400600800

10001200140016001800200022002400

quasi free π- threshold

*N. Ikeno et al., Eur. Phys. J. A 47, 161 (2011)


Target Beam Reaction ShiftsProduction 116Sn d 500 MeV 200 nA (d, 3He) 12Production 117Sn d 500 MeV 200 nA (d, 3He) 6Calibration Polyethylene, hole, Sn d 500 MeV 200 nA (d, 3He) 3

Optics Tuning Polyethylene, hole, Sn d 500 MeV 200 nA (d, 3He) 3Commissioning hole, carbon d 500 MeV ∼ 1 MHz — 6

Total — — — 30

Table 1: Requested beamtime. One shift is eight hours. Besides beamtimefor the ion optics R&D, we request the above beamtime for production,calibration, optics tuning, and detector setup.

Q value [MeV]-144 -142 -140 -138 -136 -134 -132 -130

]°re

actio

n an

gle

[

0.5

1

1.5

2

2.5

3

0

2

4

6

8

10

12

14

16

18

20

preliminary

Figure 1: A preliminary scatter plot of Q values and reaction angles measuredin the 122Sn(d, 3He) reaction. The color code represents the double differentialcross section in arbitrary units given in the color bar on the right side. Theabsolute energy calibration and acceptance correction are not finalized. Theangular dependence of the peaks are clearly different, indicating differentmomentum transfer for the reaction producing each peak.

6

1s2p

0-1°

0.5-1.5°

1-2°

2-3°

1.5-2.5°

15 hoursangular distribution!


ongoing @ RIKEN RIBF


About to start at RIBF

Nuclear chart

NNDC,BNL

systematic study of pionic nuclei in isotope / isotone chain

(i) 122Sn - pilot exp. (ii) 117Sn - first odd A target


Measurement of π-116Sn

*N. Ikeno et al., Prog. Theor. Exp. Phys. 2013, 063D01 (2013)


future prospects & summary


Future experiments

‣Unstable Sn

-Try Inverse reaction  (unstable beam on an active D2 target)

-proof of principle experiment (stable beam) in a few years

‣Isotones at RIBF

‣High resolution x-ray measurements of light pionic atoms

-use TES borometers

-pionic 3He & 4He 1s shift & width, with


Summary‣ Spectroscopy of pionic atoms - powerful tool to study

partial restoration of chiral symmetry

‣ Ongoing

- 122Sn(d,3He) - high quality data 1s, 2s, 2p, …

- 117Sn(d,3He) - first “even-A” pionic 1s, 2s, …

‣ Future

- isotones

- unstable pionic atoms using inverse kinematics

- high precision X-ray spectroscopy of light (3He, 4He, …)

pionic atoms using TES borometers

Systematic studies of deeply-bound pionic atoms at the ... · the spherical 208pb nucleus. The...

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