Stefan Meyer Institute

Kaonic Atoms - fromDANE to J-PARC
Johann Zmeskal
Stefan Meyer Institute for Subatomic Physics
Vienna, Austria

Progress on J-PARC hadron physics in 2014
November 30 - December 2, 2014

Outline• Motivation• Measuring principle• SIDDHARTA setup at DANE• Results of kaonic helium and hydrogen• Kaonic deuterium at J‐PARC• Summary

J‐PARC 2014

Motivation
Exotic (kaonic) atoms – probes for strong interaction
 hadronic shift ε1s and width Γ1s directly observable experimental study of low energy QCD
 testing chiral symmetry breaking in systems
with strangenessKaonic hydrogenscattering lengths, no extrapolation to zero energy
precise experimental data:Kp (KHe)  SIDDHARTA
Kd measurement is urgently needed determination of the isospin dependent
KN scattering lengths
J‐PARC 2014

Low‐energy K‐N systems
 Chiral perturbation theory, which was developed forp,  is not applicable for K‐N systems

Non‐perturbative
coupled channels
approach based on
chiral SU(3) dynamics
J‐PARC 2014

Improved constraints on chiral SU(3) dynamics fromkaonic hydrogen,
Y. Ikeda, T. Hyodo and W. Weise, PLB 706 (2011) 63

J‐PARC 2014

Scattering lengths
Deser-type relation1) connect the observables shift 1s and width 1s of the1s state with the real and imaginary part of the scattering length ɑ K-p(µC reduced mass of the Kp system,  fine-structure constant)i 1s  1s  2 3  c2 aK  p (1  2 c (ln   1)aK  p )21)

U.-G. Meißner, U.Raha, A.Rusetsky, Eur. phys. J. C35 (2004) 349
next-to-leading order, including isospin breaking

1a0  a1 2aK  n  a1aK  p kkaK  p  aK  n  C  a0  3a1   C
244mn  mK k2mn  mK aK  d Forming “exotic” atoms“normal” hydrogen“exotic” (kaonic) hydrogenn=1

n~25n=1
n=2

pe‐
K‐

K‐

J‐PARC 2014

X‐ray
2p → 1sK transition

Cascade processes
n~ 25

l=012

Stark‐mixing

n-1
external Auger effectchem. de‐excitation

Coulomb de‐excitation
3
X‐ray radiation
2K1

1s observable hadronic1s shift and broadening
J‐PARC 2014

X‐ray transitions to the 1s state

J‐PARC 2014

Kaonic hydrogen atoms at DANEe+‐e‐colliderAccu.

J‐PARC 2014

DANE principle• operates at the centre‐of‐mass energy of the  meson
mass m = 1019.413 ± .008 MeVwidth  = 4.43 ± .06 MeV•  produced via e+e‐ collision with(e+e‐ → ) ~ 5 μbe
e

e

e

e
e

K+e

e

e
e
e

e
e

K  production rate 2.5 x 103 s‐1→ monochromatic kaon beam (127 MeV/c)
J‐PARC 2014eeeee‐Detectors for K p experiments
KpX

DEAR

@ KEK

SIDDHARTA@ DANE

Detector

Si(Li)CCDSDD

Energy resolution

350 eV180 eV150 eVTime resolution

μs30 sμs

Thickness

mm30 μm

400 μmEfficiency at 6 keV~ 100%~ 60%~ 100%

Active area

120 cm2

116 cm2

114 cm2

J‐PARC 2014

Development of large area SDDs
SDD window frame(pure Al 99.999%)
flexible Kapton
boardspre‐amplifierboard
HV+LV distribution
board

FP‐6 EU programme:
HadronPhysics
J‐PARC 2014

Lightweight cryogenic target cellworking T 22 K
working P 1.5 barAlu‐grid
Side wall:
Kapton 50 μm
Kaon entrance
Window:
Kapton 75 μm

J‐PARC 2014

SIDDHARTA target ‐ detector

J‐PARC 2014

Advanced Seminar Series Particles and Interactions

“triple” coincidence method

X-rayKpK

K+J‐PARC 2014

Data taking scheme at DANE
K+K‐ pairs producedat DANE

Production dataK

SDDs



e

degradere

Scintillators
J‐PARC 2014K

Data taking scheme at DANE“X‐ray tube” datataken with “beam” ON

J‐PARC 2014

SDD X‐ray energy spectra“X‐ray tube” data taken

counts / 30eV

estimated systematicerror ~ 3‐4 eV

J‐PARC 2014

energy [keV]

SDD X‐ray energy spectra

J‐PARC 2014

Kaonic helium‐3 measurement
Eexp  6223.0  2.4( sta )  3.5( sys) eV
QED value: Eem= 6224.6 eV

K-3He (3d-2p)

E2 p  2  2( sta )  4( sys) eV
E2 p  Eexp  Ee.m.

Ti K

K-C

K-O-KNFirst observation of
K‐3He X‐rays
PLB 697(2011)199

J‐PARC 2014

Kaonic helium results

 calibration under control within several eV
J‐PARC 2014

Coincidence: K+KAll events
Calibration dataand SDD timing (“self trigger”) with X‐ray tube

Kaonic hydrogen

J‐PARC 2014

‐K p spectrum after BG subtraction

J‐PARC 2014

State of the art: Kaonic hydrogenε1s = ‐283 ± 36(stat) ± 6(syst) eV
Γ1s = 541 ± 89(stat) ± 22(syst) eV
SIDDHARTA

J‐PARC 2014

J‐PARC 2014

W. WeiseJ‐PARC 2014

 K d at J‐PARC
 development of a new X‐ray detector
 use of the K1.8BR spectrometer proposal submitted to J‐PARC PAC

J‐PARC 2014

20 Institutes / 10 Countries
J‐PARC 2014

Development of new SDD‐chips
 SIDDHARTA• JFET integrated on SDD• lowest total anodecapacitance• limited JFET performance• sophisticated SDD+JFETtechnology Kd @ J‐PARC• external CUBE preamplifier(MOSFET input transistor)

radiation entrance windowSDD• larger total anode capacitance• better FET performances• standard SDD technology
J‐PARC 2014

coolerCUBE

Monolithic array of 3x3 SDDs
single cell size 8 x 8 mm2
26mm

1mm dead space on each side:
80% active area
J‐PARC 2014

Best performances of new
SDD technology andCUBE preamplifier

SDD characteristics:• Area = 10 mm2• T = -40° C

55Fe spectrum

123.0 eV FWHM
1.0 s shaping time (optimum)

J‐PARC 2014

J-PARC
K1.8BR
spectrometer
K1.8BR
experimental
areabeam dump

beam sweeping
magnetliquid 3He-target
systemCDS

beam line
spectrometer

neutron counter

K d within the K1.8BR spectrometer
Solenoid
CDH...cylindrical detector hodoscope
CDC...cylindrical drift chamber

CDH
CDC

main degrader

SDD anddeuteriumtargetT0

T0.......beam line counter
T1.......beam line counter
BLC....beam line chamber

T1

J‐PARC 2014

BLCCombined target and SDD design
target cell: l = 160 mm, d = 65 mm
target pressure max.: 0.35 MPatarget temperature: 23 – 30 K
SDD active area: 246 cm2density: 5% LHD(29K/0.35 MPa)

SDD cooling and support
12 x 4 SDD arrays
K

Al reinforced side wall 75 μm Kapton
entrance window 75 μm Kapton
2014 T0start J‐PARCcounterPrediction for kaonic deuterium
Compilation of predicted Kd scattering lengths a Kˉdand corresponding experimental quantities 1s and 1sJ‐PARC 2014

Kaonic deuterium @ J‐PARC
30 kW beam power, 100 shifts
signal to background ~ 1:4
precision: shift ~56 eV, width ~139 eVAssumptions
signal: shift ‐ 800 eV
width 750 eVdensity: 5% (LHD)
detector area: 246 cm2K yield: 0.1 %yield ratio as in Kp

QED
1s

J‐PARC 2014

Summary
Kaonic X‐ray spectra measured with several targets: Kp: provided the most precise values(PLB 704 (2011) 113)
 Kd: first exploratory measurement(Nuclear Physics A 907 (2013) 69)
 K 3He: first‐time measurement(PLB 697 (2011) 199)
 K 4He: measured in gaseous target(PLB 681 (2009) 310)
 Proposal to measure K d at J‐PARC (P57)– new SDDs
– K1.8 BR spectrometer
J‐PARC 2014

Supported byP24756-N20
J‐PARC 2014

J‐PARC 2014

New SDDs ‐ present layouts
developed by Politech Milano and FBK‐Trento, Italy
Array: 9 SDDs
(8 x 8 mm2each)8 x 8 mm2
single SDD

26mm

12 x 12 mm
single SDD

FBK production:• 4’’ wafer• 6’’ wafer upgrade just finished