1st RIBF PAC

Nucleus

Pionic atom

- meson

Advanced Meson Science Laboratory Kenta Itahashi

Strong Interaction -Nucleus( Chiral symmetry in nuclear matter)

Precision Spectroscopy of Pionic Atoms in (d,3He) Nuclear Reactions

130 131 132 133 134 135 136 137 138 139E xcita tion E nergy [M e V ]

0

5

10

15

(3p ,3d ,4p ,...)(1s )( f5/2 ,p1 /2 ,p3/2 )n

-1

-1(2p )( f5/2 ,p1 /2 ,p3/2 )n

1st RIBF PAC

S m all m om e ntu m tra n sfe r(q )

(n ,p )

(d ,3H e)

0

100

200

300

400

Incident E nergy [M eV /u ]200 400 600 800

Q = -140 M eV

Q = -130 MeV

Q uas i-substitu tiona l (l~0) reaction (d ,3H e) reaction

Td=250~300 MeV/u

Experimental Principle = Missing Mass Spectroscopy

Nuclear reaction to directly populate pionic atoms.

P ion bound sta te

S. Hirenzaki, H. Toki and T.Yamazaki

1st RIBF PAC

Pion-nucleus interaction is fairly-well determined

0

10

20

30124S n (d ,3H e )

0 1 2 3 4 5B [M eV]

120S n (d ,3H e)

B [MeV]

3 60 3 65 3 7 0

116S n (d ,3H e)

B [M eV]

3He Kinetic Energy [MeV]

0 1 2 3 4 5

0 1 2 3 4 5

0

1 0

2 0

3 0

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10

20

30

1s

Calibration

Previous experiments and results

Likelihood contour in potential parameters

2001 GSI

PRL K. Suzuki et al. 92 (04) 072302

1st RIBF PACAmbiguity and error can be smaller

2) Likelihood maxima changewith different matter radius models

Strong interaction potential and nuclear density distribution arecoupled.

1) Precision can be improved

Systematic Study Determine strong interaction and nuclear matter distribution with smaller ambiguity.High Resolution Experimental resolution is improved from 400 keV < 200 keV (FWHM)

Goals in the 1st experimentother inputs: c.f. p-scattering data

1st RIBF PAC

Targets to start systematic study

i) Not measured previously ii) Measure chains of isotopes and isotones.iii) First measurement with odd-neutron number nucleusiv) Check whole system by re-measuring 124Sn & 120Sn

Selection criteria

1st RIBF PAC

Experimental SetupBigRIPS as Spectrometer

Beam: 250 MeV/u deuteron beam Intensity=1 x 1012/s p/p = 1 x 10-3

Target: 5~15 mg/cm2 w. > 5 holders

F5: focal planeMW Drift Chambers 8 planes, 768 wires < 0.3 mm resolutionPlastic Scintillation

counters

Target - F5 Dispersive focus (D=5000 mm)

F5 – F7: PIDTOF and E

Resolution: ~200 keV (FWHM)

1st RIBF PACKeys to High Resolution Spectroscopy = Beam Optics

Target

Resolution (keV, FWHM) Beam p/p 100 Target width 90Target thickness 140----------------------------- ~ 200

If dispersion matching is achieved.

~140SRC-TA:Analyze deuteron beammomentum

TA-F5: F5 position depends only on missing mass in TA

F5

1st RIBF PAC

FY 2006-3

FY 2006-4

FY 2007-1

FY 2007-2

FY 2007-3

DAY-1

Beam

MW Drift Chamber

Segmented Scintillation Counters

Beam Optics Calculation

Target Fabrication

Electronics/Gas System/Cables

DAQ

Beam Test Run

Preparation Status and Schedule (slightly changed due to budget situation)

Beam opticsBeam property measurement

1st RIBF PAC

Study of pionic atoms has been yielding fruitful results on the -nucleus s-wave interaction, with interesting implications for the study of chiral restoration in a nuclear medium.

Theoretical evaluation of expected cross section is reliable and is ongoing. (Nara Women's Univ. theory group)

RIBF is the most suitable facility to proceed the study and to perform the systematic spectroscopy. Systematic study is expected to lead to smaller ambiguities in determination of the strong interaction and nuclear matter distribution.

Preparation is now in progress.

Summary

1st RIBF PAC

Human ResourcesRIKEN (Iwasaki-lab) + Tokyo Tech. K. Itahashi, M. Iwasaki, H. Ohnishi, S. Okada, H. Outa, M. Sato, T. Suzuki, T.Yamazaki (Detectors + Electronics + Gas handling) RIKEN (Accelerator) M. Wakasugi, Y. Yano, (Collinear Laser Spectroscopy)GSI (FRS-group) H. Geissel, C. Nociforo, H. Weick (Beam Optics Calculation and Test)University of Tokyo R.S. Hayano, S. Itoh, N. Ono, H. Tatsuno, (Physics + Detectors)Nara Women’s University S. Hirenzaki, R. Kimura, J. YamagataStefan Meyer Institute P. Kienle, K. Suzuki (Target + Physics)Stockholm University P.E. Tegner, K. Lindberg, I. Zartova (Detectors + Electronics + Gas handling)

1st RIBF PAC

Spare

1st RIBF PAC

Readout Electronics + DAQ

MWDC: 8 planes x 48 wires x 2 sets = 768 ch (TDC) 16ch PreAmp + Amp = newly designed by KEK ⇒ fed to VME 64ch TDC (AMT-KEK)

Scintillation counters: 20 ch (QDC+TDC) ⇒ fed to VME 16ch QDC & 16ch TDC (CAEN)

Trigger Condition SCF5 × SCF7 ~200 Hz ⇒ (5 mg/cm2 target + 1012/sec beam) c.f. background proton 0.25 MHz

Realistic Numbers

Remote Controllable Modules (Since we have no access to the cave)

Camac? Presently no idea.⇒

1st RIBF PAC

1st RIBF PAC

Strong interaction optical potential

Uopt= Vs-wave + Vp-wave

Vs-wave = b0 (r) + b1(r) + B02(r)

(r)=n(r)+p(r) =nuclear density

(r)=n(r)-p(r)

scattering experiment

b0

isoscalar part parameter

b1

isovector part parameter

Physics Motivation (Strong interaction)

PLB469(99)Schroeder et al.

A=1 -hydrogen, -deuterium high precision spectroscopy B/B < 1 % @ PSI

b0= b1=

1st RIBF PAC

Four step calibration of incident energy in 100 keV precision

Step 0. Set BigRIPS to primary deuteron beam rigidityStep 1. Measure 12C3+ beam velocity by Collinear laser spectroscopy.Step 2. Calibrate BigRIPS by measuring 12C3+ beam position at focus. Step 3. Keep BigRIPS and measure deuteron beam position at focus.

deuteron K=500 MeV p=1457.9 MeV/c 12C3+ z=3, p/z = 1457.9 MeV/c therefore p = 4373.85 MeV/c --> K = 825.48 MeV beta = 0.61371 gamma = 1.26658

relativistic doppler correction w' = w * gamma (1 + beta cos theta)

12C3+ transition 0.293 Hartree (J. Phys. B: At Mol Opt Phys 34 (2001) 1079-1104 M.Godefoid )----> w = 7.969 eV (1 hartree = 27.211 eV) w' = 5.442 eV -> 231 nm

So, what we need is 231 nm laser and 12C3+ 825 MeV (=70 MeV/u).

1st RIBF PAC

How to measure the beam energy?

NIM A419 (98) 50. Wakasugi et al.

Laser

Fluorescence

10-6 accuracy of is possible.

Collinear laser spectroscopy

Systematic error reduced.

1st RIBF PAC

Antiproton absorption measurement neutron density distribution

1st RIBF PAC

0.10

0.05

0.00

-0.05

-0.10 -0.05 0.00 0.05 0.10

radius c-c0 [fm]

Pionic atoms are sensitive to nuclear radii

2 param. Fermi model

1st RIBF PAC

0

5

10

-B [MeV]

1s

2s

2p

3d

Level diagram(Pionic lead)

with Finite size Coulomband strong interaction

Nuclear Absorption

Stopped pion method does not work effectivelyto investigate “deeply bound pionic states”where pion and nucleus has large overlap.

1st RIBF PAC

-3

-2

-1

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1

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3

4

5

0 200 400 600 800 1000 1200

ExtractionTime [ms]

Let me talk more about technical details…

GSI-SIS

Systematic errorarising from uncertaintyin the beam energyis large.

What was the beam energy?

0.1

% m

omen

tum

drif

t

1st RIBF PAC

Strong interaction optical potential

Uopt= Vs-wave + Vp-wave

Vs-wave = b0 (r) + b1(r) + B02(r)

(r)=n(r)+p(r) =nuclear density

(r)=n(r)-p(r)

scattering experiment

b0

isoscalar part parameter

b1

isovector part parameter

Physics Motivation (Strong interaction)

PLB469(99)Schroeder et al.

A=1 -hydrogen, -deuterium high precision spectroscopy B/B < 1 % @ PSI

b0= b1=

1st RIBF PACCost Estimation

(kYen)MWDC 6,000PreAMP + Amp 2,000VME TDC (LVDS) 4,500VME Crate + Master 1,400VME QDC + TDC 1,200NIM Modules 2,600MWDC HV 1,500PMT HV 1,000Cables 800Camac? 1,200Segmented Scintillator 1,000PMT 2,000Gas system 1,000--------------------------------------- 26,200