New experimental results on the strong interaction in kaonic atoms

New experimental results on the strong interaction in kaonic atoms

J. MartonStefan Meyer Institute

Austrian Academy of Sciences, Vienna

Seminar TUM, 27 June 2011

LEANNIS


Outline• Low-energy antikaon interaction – motivation of new studies

• Solved puzzlesKaonic atoms:– Kaonic hydrogen (strong interaction effect on 1s)– Kaonic helium isotopes He-3,4 (strong interaction on 2p)

• Open questions and future challengesKaonic atoms– Precision data on kaonic deuterium– Precision data on kaonic atoms Z>2Relation kaonic nuclei:– Lamda(1405) and ist relation to the quest of bound strange

nuclear systems (K-pp, K-ppn …)

• Summary and Outlook

New data from

SIDDHARTA at LN

F


The field

• Studies of atomic bound systems with strangeness (hadronic/kaonic atoms) provide unique access to strong interaction of antikaons at very low energies (i.e. in kaonic atoms).

• Search for exotic nuclei bound by antikaon(s)

• Fascinating research field involving different fields in physics (particle physics, nuclear physics, atomic physics) and energies from GeV to eV.

• Unique research infrastructures in Europe: DAFNE/LNF, GSI, Jülich.

Sources of experimental information on the low energy (anti)kaon-nucleon interaction

• Kaon-proton scattering data (old data with large errors, above threshold extrapolation)

• πΣ mass spectrum new studies• Threshold decay ratios• X-ray data of light kaonic atoms (K-p, K-d, K-He)

– Kaonic hydrogen increase precision, threshold data important input for theory

– Kaonic deuterium first experimental studies– Kaonic helium-4 2p shift small (KEK 570),

„superstrong“ antikaon nuclear interaction ruled out?• Reliable theory has to cope these informations


Motivation for new studies• The low-energy kaon-nucleon interaction is neither simple nor well understood:

• Central importance for the physics of strong interaction has the dynamics driven by

chiral symmetry breaking in low-energy QCD.

• Problems arise from the existence of hyperon resonances like the famous Λ(1405)

and 2/3 nucleon K- absorption (c.f. E. Oset, H. Toki, PRC74 (2006) 015207) possibly

imitating bound states.

• The development of reliable theories is asking for precision data on the threshold

observables (e.g. shift/width of kaonic atom states).Seminar TUM, 27 June 2011

Interesting question:Two-pole structure??Λ(1405) & Λ(1420) and their impact


L ow E nergy A ntikaon N ucleus N uclei I nteraction S tudies

LEANNIS

EU-FP7

Solved Puzzles



Kaonic Hydrogen


Kaonic hydrogen and deuterium• Principal interaction = electromagnetic.

• Strong interaction manifests in hadronic shift and width of the 1s state energy displacement from the electromagnetic value of the 1s state and broadening due to K- absorption

• calculated solving the Klein-Gordon (KG) equation and taking into account vacuum polarization (VP) and final size (FS) effect (accuracy ~1eV).

• Strong interaction effect on 2p state is weak (meV) and experimentally undetermined, nevertheless has severe consequences for the x-ray yield.

FSVPKGcalcme

s

calcmes

measss

EEEE

EE

.)(.

1

.).(.1

.11


Energy scales involved

• Phi-meson formation 1.020.000.000 eV• K- energy (Phi decay) 16.000.000 eV• Kα transition energy in K-p 6.500 eV• Strong interaction shift 280 eV• Accuracy of shift determination few 10 eV

Example: Kaonic hydrogen at DAFNE/LNF

Challenge: Precision x-ray spectroscopy in a particle accelerator environment

Particle physics meets atomic physics


Kaonic hydrogen "puzzle"

KpX @ KEK

DEAR@LNF

X-ray experiments gave a positive energy shift of the 1s state by strong interaction in kaonic hydrogen.

in the contrary scattering experiments indicated a negative energy shift.

This puzzling situation was clarified in the KpX experiment and later by our group with DEAR.

Threshold data on kaonic hydrogen


DEAR (2005)1s = - 193 ± 37 (stat.) ± 6 (syst.) eV1s = 249 ± 111 (stat.) ± 30 (syst.) eV

aK-p = (-0.468 ± 0.090 ± 0.015) + i(0.302 ±0.135± 0.036) fm

KpX (1998)1s = - 323 ± 63 (stat.) ± 11 (syst.) eV1s = 407 ± 208 (stat.) ± 100 (syst.) eV

aK-p = (-0.78 ± 0.15 ± 0.03) + i(0.49 ±0.25± 0.12) fmusing Deser-Trueman (i.e. lowest order)

Most precise values for shift and width from DEAR experiment (CCDs)But still precision limited (e.g. error bar of width > 50%)shift vs. width (1 σ errors) see below

Result on K4He 2p shift (E570 @ KEK)

• Clarification of along-standing puzzle

puzzle



Solved puzzles – Status before SIDDHARTA

• Kaonic hydrogen puzzle was qualitatively solved (sign) but precision was limited, furthermore the case of kaonic deuterium was unexplored

• Kaonic helium-4 puzzle was quantitatively solved but verification was asked for and the strong interaction in helium-3 was unexplored this was solved by SIDDHARTA.

• On the other hand precision data are requested for reliable theoretical description of the low-energy anti-kaon nucleon interaction and in the context of the existence of kaonic nuclear bound states

New experiments -- new (x-ray) detectors

• Silicon Drift Detectors with large active areaactive area 100 mm2

• Excellent energy resolution, timing capability

• Compact design, arrangement in array

• 2 different SDD types for exotic atom research

SDD with external FET(commercial product, KETEK)system studied: K-4He (E570/KEK)

SDD with on chip integrated FET SIDDHARTA (JRA10/EU-FP6)systems studied: K-p, K-d ….



SIDDHARTA Collaboration

Garching Munich Vienna

Bucarest


Excellent for low-energy kaon physics:

kaonic atoms

Φ → K- K+ (49.1%) Monochromatic low-energy K-

(~127MeV/c)• Less hadronic background due to the beam ( compare to hadron beam line : e.g. KEK /JPARC)

Electron-positron collider DAFNE at LNF


DAFNE Luminosity

DAFNE operated with crab waste system Higher luminosity

SIDDHARTA is taking data only betweeninjections (blue dots, yellow line)

Under good conditions duringSIDDHARTA DAQ L ~ 2.8 1032 – 1.0 1032 cm-2 s-1

Comparison to 2002 DEAR experiment:~ 3.0e31 cm-2 s-1

now up to 10 times higher !

SIDDHARTA integrated luminosity on 23 Oct 2009: ~ 8 pb-1 !

18

calibration


SIDDHARTA SDD Array144 SDDs =144 cm2 active area


SIDDHARTA SDD

1Chip : 1 cm2

Seminar TUM, 27 June 2011 21

xy

z

SIDDHARTA Setup


New X-ray detectors (SDD silicon drift detectors) timing capability background

suppression by using the kaon - X ray time correlation

excellent energy resolution high efficiency, large solid angle performance in accelerator environment

Scint

SDDs

Triple coincidence: SDDX * ScintK * ScintK

Scheme of SIDDHARTA

Fe-

Goal: measure the shift and broadeningof the X ray transition of kaonic atomsWith high precision.

Scint

e+

K-

K+

SDDs

X

22


Background suppression

X-ray energy [keV] time [83 ns/ch]

Efficient background suppression by using the kaon-xray correlation


Beam pipe in e+e- intersection of SIDDHARTA

SIDDHARTA used the KLOE intersection of DAFNE

Luminosity increased with new system providing a large crossing angle (crab waist system)

Kaon window

Kaon detectors sitting below and above the intersection


SIDDHARTA data overview


- Kaonic Hydrogen: 400pb-1, most precise measurement, submitted for publication, PLB, arXiv:11053090v1

- Kaonic deuterium: 100 pb-1, as an exploratory first measurement ever, advanced analysis

- Kaonic helium 4: first measurement ever in gaseous target; published in Phys. Lett. B 681 (2009) 310; NIM A628 (2011) 264 and Phys. Lett. B 697 (2011)

- Kaonic helium 3: 10 pb-1, first measurement in the world, published in Phys. Lett. B 697 (2011) 199

SIDDHARTA Measurements:


K-He4PLB681(2009)310

Kaonic Helium-4 @ SIDDHARTA

eV)syst(2)stat(60..exp

meEEE


K-3He (3d-2p)

Ti KaK-C K-O K-N

eV)(4)(222 sysstaE p

1st Me3asurement: Kaonic Helium-3

..exp2 mep EEE

eV)(5.3)(4.20.6223exp sysstaE

eV6.6224.. meEQED value:

arXiv:1010.4631v1 [nucl-ex], PLB697(2011)199

First measurement ever

Integr. Lum. = 10 pb-1 only!!!


Kaonic Helium-3 relative transition yields

preliminary (Ph D thesis A. Scordo)


Kaonic Helium-4 relative transition yields

preliminary (Ph D thesis A. Scordo)


Comparison of resultsShift [eV] Reference

KEK E570 +2±2±2 PLB653(07)387

SIDDHARTA (He4 with 55Fe) +0±6±2 PLB681(2009)310

SIDDHARTA (He4) +5±3±4 arXiv:1010.4631,PLB697(2011)199SIDDHARTA (He3) -2±2±4

*error bar 22 )()( syststat


K4He vs. K3He

SIDDHARTAK4He ε2p= +5 ± 3(stat) ± 4(syst)K3He ε2p= -2 ± 2(stat) ± 4(syst)

Y. Akaishi, Proc. EXA05, Austrian Academy of Science Press, eds. A. Hirtl, J.M., E. Widmann, J. Zmeskal

Isotope shift seems to be rather smallbut isotopic effect might be detectable


Outlook: Experiment on K3He at J-PARC

The experiment E17 at J-PARC has European partners (LNF/Italy, SMI/Austria). SMI is responsible for the x-ray detector systems.The experiment E17 is in preparation, schedulestrongly depends on beam availability at J-PARC after earthquake.

Independent precision measurement KHe-3 at J-PARC- Enhancing the precision in ε2p


e e

SDDs

Ti/Cu foil

X-ray tube

Data taking at DAFNE -Calibration

calibration data

Estimated systematic error ~ 3-4 eV


e e

K

K

SDDs

degrader

Scintillators

Production data

Data taking at DAFNE - Production


Kaon

BG

Kaon gateBackground gate

SDD Timing vs. Energy

(asynchronous background)

for K-p data


Kaonic hydrogen

Hydrogenspectrum

Kα Kβ higher

Background estimation

KO76 KN65Cu

Ti Kα

Ti Kβ

KC65

KC75KO65

KC54

KAl87

EM valueK-p Kα

simultaneousfit

Deuteriumspectrum


EM valueK-p Kα

Kaonic hydrogen

Kα Kβ

higher

Residuals of K-p x-ray spectrumafter subtraction of fitted background


1S= −283 ± 36(stat) ± 6(syst) eV

1S= 541 ± 89(stat) ± 22(syst) eV

With relative yields of K lines known error on position < 20-25 eV

KAONIC HYDROGEN results

Submitted to Phys. Lett. (May 2011)


SIDDHARTA

Kaonic hydrogen result (2011)


- most reliable and precise measurement ever

- need to study K-d! SIDDHARTA-2

Kaonic Hydrogen with SIDDHARTA

arXiv:1105.309016 May 2011

KN interaction at threshold


B. Borasoy, R. Nißler and W. Weise, Phys. Rev. Lett. 94, 213401 (2005)

K-p: repulsive character at threshold, attractive below threshold

threshold

DEAR data

real part

Imag. partSIDDHARTA

Re

Im

Λ(1405)


Kaonic deuteriumOnce the shift and width of the 1s level for kaonic hydrogen and

kaonic deuterium are measured -) scattering lengths a0, a1

(isospin breaking corrections):

111

111

fmeVai

fmeVai

dKss

pKss

1

10 )(21

aa

aaa

dK

pK

“To summarize, one may expect that the combined analysis of the forthcoming high-precision data from DEAR/SIDDHARTA collaboration on kaonic hydrogen and deuterium will enable one to perform a stringenttest of the framework used to describe low–energy kaon deuteron scattering, as well as to extract the values of a0 and a1 with a reasonable accuracy. However, in order to do so, much theoretical work related to the systematic calculation of higher-order corrections within the non-relativistic EFT is still to be carried out.” (from: Kaon-nucleon scattering lengths from kaonic deuterium, Meißner, Raha, Rusetsky, 2006, arXiv:nucl-th/0603029)


KN(6-5)

KC(6-5)

KO(6-5)

KC (6-4)

KAl (8-7)

KC (7-5)

X ray energy (keV)

Kaonic deuterium spectrum (preliminary:fit for shift about 500 eV, width about 1000eV, Ka / Kcomplex = 0.4

KO(7-6)

KO(9-7)

KTi (11-10)

Cu Ka

KC (5-4)

KAl (7-6)KN

(5-4)

KAl (10-8)

Pb Lb

Kd KcomKd

Ka


K-p most precise measurement; paper submitted for publication

K-d first measurement ever, exploratory measurement, small signal, significance ~ 2s, paper in preparation; SIDDHARTA-2

K4He measured for the first time in gaseous target, two papers published

K3He first time measurement , paper published

Summary of SIDDHARTA analyses status

Some open questions

• Precision data on antikaon-nucleon interaction requires study of KD to extract scattering lengths a0 and a1, important input for theory.

• Λ(1405) – pole structure ? Consequences?• Strength of antikaon-nucleon interaction below

threshold.



New ideasSIDDHARTA-2

SIDDHARTA2


- Kaonic deuterium measurement

- Kaonic helium transitions to the 1s level - X-ray studies of other light kaonic atoms (KO, KC,…)

- Heavier kaonic atoms measurement (Si, Pb…)

- Kaon radiative capture – L(1405) study

SIDDHARTA-2 Strategy


New precision studies of the strong interaction in kaonic atoms at DAFNE

Enriched physics case (keV-MeV γ detection):

Proposal submitted in 2010

Addendum 2011


• new target design

• new SDD arrangement

• vacuum chamber

• more cooling power

• improved trigger scheme

• shielding and anti-coincidence

SIDDHARTA-2 setup improvements


SIDDHARTA-2 Setup


Trigger scheme, shielding


SIDDHARTAautumn 2009

SIDDHARTA-2new - geometry- gas density- timing resolution

improve-mentfactor

gas cell: diameter x height (cm) 13.9 x 15.5 17 x 14

entrance distance from IP (cm) 20 15

gas density rel. LHD < 1.5 % 3 %

upper trigger scint. 4.9 x 6 cm2

diameter 9 cm

dist. from IP (cm) 6 13

triggers per kaonpair 9.4 % 5.3 %

K- gasstops per kaonpair (triggered) 0.78 % 1.94 %

Signal 827 /pb-1 2035 /pb-1 2.5trigger per signal 188 39 4.8 synchr. continous backgr. /Signal /keV at ROI

0.3 % 0.08 % 3.8

KC / Signal (kaonic lines from wall stops) 4 % 0.2 % 20SDD timing resolution (ns) 750 500 1.5


Kaonic deuterium with SIDDHARTA


Kaonic helium K lines?Traditionally 2p orbit is assumed to be last orbit, but there might be a chance to detect also the 2p-1s transition (E~30 keV) giving significant information about the antikaon-nucleus interaction.

???

Shift 2p ~ 0 eV

D.N. Michael, PR158 (1967) 1343G.R. Burleson et al., PRL 15 (1965) 70

???


New experiments

• Spectroscopy of kaonic atoms with Z>2 improving the precision of the data set

C.J. Batty et al., Nucl. Phys. A329 (1979) 407-426

e.g. K-Oε=-25±18 eV


The Lamba(1405) Resonance

• Generated by the attractive Kbar-N interaction• Quasi-bound state decaying into Σπ• Predicted by Dalitz and Tuan in 1959• After more than 50 years still a challenging

object in experiment and theory• Relation to nuclear bound states mediated by

the attractice Kbar-N interaction


Λ(1405) structure- a key topic• **** star object in PDG• Structure of Λ(1405)?

• Akaishi-Yamazaki proposed Λ(1405) to be an K-p bound state opening the direct opportunity („doorway“) to produce kaonic nuclei (e.g. K-pp)

• V.K. Margas et al. Phys.Rev. Lett. 95 (2005) 052301:2-pole structure

R. J. Hemingway, Nucl. Phys. B253, 742 (1985).

M=1406.5 4.0 MeVΓ=502 MeV


Studies on Λ(1405)

• ANKE • HADES • J-Lab• J-PARC• SIDDHARTA2

R. J. Hemingway, Nucl. Phys. B253, 742 (1985).

Search forK-p Λ(1405) + With SIDDHASRTA-2(after an idea of S. Wycech)


Outlook• SIDDHARTA2 in preparation• Highest priority: Kaonic deuterium x-ray spectrum• Impact for theory, extraction of isospin-dependent

scattering lengths a0 and a1

• Search for K-transition in K-He• K-p Λ(1405) + • Independent information on Λ(1405) • Close collaboration of experimentalists and

theoreticions extremely important (LEANNIS)• LEANNIS in HadronPhysics2 till end of 2011• LEANNIS in HadronPhysics3 accepted by EC (2012-2014)


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