systematic studies of deeply-bound pionic atoms at the ... · the spherical 208pb nucleus. the...
TRANSCRIPT
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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
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Hayano, MESON 2014, Kraków
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
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Hayano, MESON 2014, Kraków
why? - chiral condensate
Already discussed by S. Hirenzaki
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Hayano, MESON 2014, Kraków
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
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Hayano, MESON 2014, Kraków
Deeply bound pionic atoms
300 MeV
Normal NuclearDensity
ρT
||–-(250 MeV)3
-35%
5ρ0
Quantitative evaluation of chiral order parameter
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Hayano, MESON 2014, Kraków
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
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Hayano, MESON 2014, Kraków
GSI experiment (pionic Pb, Sn)
successfully completed some 10 years ago
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Hayano, MESON 2014, Kraków
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
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Hayano, MESON 2014, Kraków
Pionic X-rays
Strong Interactionπ absorption
Invisible
“deep” states invisible to X-rays
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Hayano, MESON 2014, Kraków
“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
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Hayano, MESON 2014, Kraków
(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
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Hayano, MESON 2014, Kraków
SETUP
d
3He
FRS
250
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Hayano, MESON 2014, Kraków
Pionic Sn at GSI
1s
Calibration
115Sn
119Sn
123Sn
NNDC,BNL
Nuclear chart
K. Suzuki et al., PRL92 072302 (2004)
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Hayano, MESON 2014, Kraków
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
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Hayano, MESON 2014, Kraków
why further measurements?
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Hayano, MESON 2014, Kraków
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
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Hayano, MESON 2014, Kraków
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
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Hayano, MESON 2014, Kraków
piAF @ RIBF - what can be improved?
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Hayano, MESON 2014, Kraków
b1 with better precision - longer lever arm
Vs = b0� + b1(�n � �p) + B0�2.π-A s-wave interaction → 〈qq〉
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Hayano, MESON 2014, Kraków
b1 with better precision - 2D coverage
Vs = b0� + b1(�n � �p) + B0�2.π-A s-wave interaction → 〈qq〉
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Hayano, MESON 2014, Kraków
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
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Hayano, MESON 2014, Kraków
pilot experiment @ RIBF
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Hayano, MESON 2014, Kraków
The pilot experiment @ RIBF
NNDC,BNL
First Experiment
Nuclear chart
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Hayano, MESON 2014, Kraków
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
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Hayano, MESON 2014, Kraków
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)
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Hayano, MESON 2014, Kraków
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!
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Hayano, MESON 2014, Kraków
ongoing @ RIKEN RIBF
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Hayano, MESON 2014, Kraków
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
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Hayano, MESON 2014, Kraków
Measurement of π-116Sn
*N. Ikeno et al., Prog. Theor. Exp. Phys. 2013, 063D01 (2013)
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Hayano, MESON 2014, Kraków
future prospects & summary
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Hayano, MESON 2014, Kraków
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
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Hayano, MESON 2014, Kraków
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