The AMADEUS project – precision studies of the low-energy antikaon nucleon interaction Johann Zmeskal, SMI – Vienna, Austria for the AMADEUS collaboration

The AMADEUS project – precision studies of the low-

energy antikaon nucleon interaction

Johann Zmeskal, SMI – Vienna, Austria for the AMADEUS collaboration

International Workshop on Hadronic Atoms and Kaonic Nuclei ECT*, Trento 12 – 16 October 2009

AMADEUS at DANE

Antikaon

Matter

At

DANE:

Experiments with

Unraveling

Spectroscopy

International Workshop on Hadronic Atoms and Kaonic Nuclei

AMADEUS collaboration


110 scientists from 34 Institutes of 14 Countries

Letter of Indent

Study of deeply bound kaonic nuclear states

at DANE2

March 2006

Introduction

Investigations of antikaon-mediated bound nuclear systems were done, are ongoing or planned at several facilities - KEK, LNF, GSI, J-PARC, CERN-AD

Next-generation experiments should be exclusive, i.e. require the measurement of formation and decay

AMADEUS @ DAΦNE2 aims to do that with - stopped K− in low-density gas targets - unique features available at DAΦNE2 - measurement of all decay particles, charged and neutral, using the KLOE detector


DAFN at LNF


AMADEUS’s main aim is to perform a full acceptance, high precision measurement of antikaon-mediated bound nuclear systems – studying the formation as well as the decay process, by implementing the KLOE detector with an inner AMADEUS dedicated setup, containing a cryogenic target and a trigger system (and an inner tracker in a second phase).

First actions:Results of the KLOE data analysis were presented by O. VazquezTest measurements of the AMADEUS trigger system were presented by A. Scordo

The goal of AMADEUS


The experimental program - 1

study of the (most) fundamental antikaon-mediated bound nuclear systems, the kaonic dibaryon states:

ppK- and (pnK-)

produced in a 3He gas target, by their formation and decay processes

and as next step, the kaonic tri-baryon states:

ppnK- and (pnnK-)

produced in a 4He gas target, by their formation and decay processes


The experimental program - 2

Low-energy charged kaon cross section on p, d, He-3 and He-4, for K- momentum lower than 100 MeV/c

The K- nuclear interactions in Helium (poorly known – based on one paper from 1970 …)

Properties of L and charged S´s

Resonance states as L(1405) or the S(1385) in addition their behaviour in a nuclear

mediumcan be studied


Production methods of antikaon-mediated bound nuclear cluster

stopped K- reactions on light nuclei

in-flight K- reactions

protons on proton (or light nuclei)

heavy ion collisions

strangeness production in antiproton annihilation


tri-baryon systems with S = -1

formation process:

K- + 4He ppnK- + n

possible decay channels:

ppnK- + d

+ p + n - + p +

p 0 + d 0 + p + n

L p + - n + 0

S- n + - S0 +


Hyperon production

K-N Y


Non-mesonic absorption

K-NN YN


13

Schematicside view ofthe KLOE detectorwith AMADEUScomponents added:

e+ e-

K-

K+

Amadeus @ KLOE


KLOE CDC

= 0.289 ± 0.003

Lambda invariant mass,

using existing KLOE data (O. Vazquez

Doce)Minv= 1115,723 ±0. 003stat (MeV/c2)

PDG: MΛ= 1115,683 ±0.006stat±0.006syst (MeV/c2)

systematic dependents on momentum calibration, has to be evaluated using 2-body decays: K±→μ±ν and K±→π±π0


KLOE calorimeter


Reconstructed Ks mass

Photon energy resolution (E)/E = 5.7%xE(GeV)-1/2

time resolution t/t = 54 [ps]xE(GeV)-1/2

Ks oo, with o


Neutron detection efficiency

Threshold at 1 MeVThreshold at 3 MeV

MC simulation, confirmed with measurements at TSL (Uppsala


AMADEUS @ KLOE


AMADEUS @ KLOE


half-toroidal cryogenic target cell

1st inner-layer ofscintillating fibrefiber size: 1x1mm2

2nd inner-layer ofscintillating fibrefiber size: 1x1mm2

three outer-layersof scintillating fibrefiber size: 1x1mm2

AMADEUS setup Low-mass cryogenic gas target cell:T = 10 KP = 1.0 barRin = 5 cmRout = 15 cmL = 20 cm


The AMADEUS trigger system

• Cilindrical layer of scintillating fibers surrounding the beam pipe to trigger K+ K- in opposite directions

• Readout to be done by SiPM

• Inner tracker (eventually, a first tracking stage before the DC)

• Target ( A gaseous He target for a first phase of study)

• Trigger (1 or 2 layers of ScFi surrounding the interaction point)

target

Trigger systemScFi + SiPM readout

K+

K-

A. Scordo


Sketch of the AMADEUS setup


View in beam direction

Cryo target cell

Beam pipe: Æ= 60 mm,thickness = 0.25 mmmade of BeAl alloy

Kaon trigger


AMADEUS setup II

full toroidalcryogenictarget cell

vacuum chamber

thin-walledbeam pipe

2 outer-layer ofscintillating fibrefiber size: 1x1mm2

kaon trigger:2 inner-layer ofscintillating fibrefiber size: 1x1mm2


Tracking device:TPC-GEM or3-4 C-GEMs

Target system:cylindrical

cryogenic cellin vacuum chamber

Kaon trigger:Scint. fiberswith SiPMs

25

AMADEUS setup – phase II

inner tracker

FEE

AMADEUS setup – phase II

Cylindrical GEMs


Beam-pipe solutions


Number of charged kaon pairs

N = L s b = 2.9 × 109 K-

2 fb

-1 = 2

× 1

039 c

m-2

inte

grat

ed

lum

inos

ity

0.49

bra

nchi

ng

ratio

for K

±

Total number of produced charged Kaon pairs for L = 2 fb-1

1 barn = 10-24 cm2

1 femtobarn = 10-15 barn = 10-

39 cm2

3 × 1

0-3

0 cm

2

F p

rodu

ctio

n

cros

s se

ctio

n


Number of events for the channel:

K- +4He (K-ppn) + n with (K-ppn) +d

Assumptions: 20% stopped kaons Y = 5.10-4 (K-ppn) formation

BR for decay channel = 10% (with p + -)

For an integrated luminosity of 2 fb-1:

N = 3x109 x 0.2 (stops) x 5x10-4 (Y) x 0.1 (BR) = 30 000 ev

Detection efficiency for charged particles (40%) 12 000 ev

Detection efficiency for neutrons (30%) 3 600 evfor which both missing and invariant mass can be reconstructed International Workshop on Hadronic Atoms and Kaonic Nuclei

Beam time request

• 2 fb-1 of integrated luminosity with He4 target in order to study the tribaryon (S=-1)

• 2 fb-1 of integrated luminosity with He3 target in order to study the dibaryon (S=-1)

overall integrated luminosity of 4 fb-1

With the luminosity upgrade of DANE, the machine should deliver at least 500 pb-1/month, which means that the overall AMADEUS Phase-1 program could be completed in about 8 months


AMADEUS R&D, construction and tests the R&D for AMADEUS are ongoing, construction, assembly and tests have to be finished 2010/11

roll-in of AMADEUS roll-in 2011/12 (end of KLOE step 0)

AMADEUS data taking for an integrated luminosity of about 4 fb-1

AMADEUS time schedule


Conclusion

The goal of AMADEUS is to perform a complete measurement - formation and decay processes - of di - and tri-baryon antikaon-mediated bound nuclear systems in helium-3 and helium-4.

It will contribute to a definite answer of the existence of antikaon-mediated bound nuclear systems in light systems.

The antikaon – nucleon/nucleus interaction will be studied in detail with AMADEUS.


Documents

The AMADEUS project – precision studies of the low-energy antikaon nucleon interaction Johann Zmeskal, SMI – Vienna, Austria for the AMADEUS collaboration