From kaonic atoms to kaonic nuclei with DAFNE2

1
From kaonic atoms to kaonic nuclei with
DAFNE2  28-30 November 200531th LNF
Scientific Committee C. Curceanu and J.
Zmeskal DEAR/SIDDHARTA Collaboration
 
 
 Proposal of an international facility at
DA?NE2
2
(pre)Letter of Intent  The case of deeply bound
kaonic nuclear states Proposal of an
international facility at DA?NE2  September
2005  DEAR/SIDDHARTA Collaboration Manifestati
on of interest from Institutions of-          
Austria-           Canada-          
France-           Germany-          
Hungary-           Italy-          
Japan-           Poland-          
Romania-           Russia-          
Sweden-           USA-          
Letter of Intent -gt Spring 2006
31th LNF Scientific Committee
CC,JZ / Nov. 29, 2005
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AntikaonicMatterAtDAFNE anExperimentUnraveli
ngSpectroscopy
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Contents1) Brief sketch of the
scientific case of kaonic nuclear clusters2)
From kaonic atoms to K-nuclear bound states 3)
Current and future experiments gt the unique
features of DAFNE25) Features and
identification of the setup and the
experimental programme 6) First steps towards
AMADEUS7) Formation of an international
collaboration 8) Conclusions
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A new paradigm in strangeness nuclear physics,
with important consequences in fundamental
physics, is represented by the recently observed
Deeply bound Kaonic Nuclear stateswhose first
experimental indications are being produced at
- KEK and- LNF - GSI- BNL gt cold and
dense nuclear system
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KN interaction

• Until 1997 Confusing situation (part due to KH
  puzzle)
• 1997 KpX experiment at KEK Iwasaki et al.
  PRL(1997)
• K-p atom shift DE1s repulsive-type,
• Indicating the K-p interaction is strongly
  attractive
• 2002 DEAR results -gt PRL 94, 212302 (2005)
• Consistent with the view that
• L(1405) 1s bound state of K-p
• Scattering data (no data at low energy)
• 2002 Akaishi-Yamazaki constructed Nuclear K
  bound states in light nuclei

Y. Akaishi T. Yamazaki, Phys. Rev. C 65 (2002)
044005
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Kaonic Nuclear Bound States

• Believed (lt2002) to be non-existing G gt EB
• Akaishi-Yamazaki (2002) predicted
• - K--p interaction so strong that it
• - might shrinks nuclei --gt deeper bound
  states
• - deep enough that
• the main decay channel KN--gtSp closed
• - strongly (deeply) bound states
• EB gt 100 MeV narrow bound states (Glt10 MeV)

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First experimental indications E471 Experiment
Results 4He(K-stopped, n) and 4He(K-stopped, p)
missing mass spectra
(M. Iwasaki et al., nucl-ex/0310018 v2)
S0(3115) M 3117 3.8-2.0(sys)/-0.9 (stat) Glt
21.6 MeV, B -194 MeV with respect to
K-pnn rest mass Predicted NOT to exist! (B20
MeV G100 MeV)

S(3140) M 3117 3.8-2.0(sys)/-2.3 (stat) Glt
21.6 MeV, B -169 MeV with respect to
K-ppn rest mass Predicted with B 110 MeV

M. Iwasaki et al., NIM A 473 (2001) 286
Y. Akaishi T. Yamazaki, Phys. Rev. C 65 (2002)
044005
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3He ---gt 3HeK- shrinkage !!
(AMD method Dote et al. 2002)
rc 4 -10 r0

• Explore cold
• and dense
• nuclear states

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Exploring dense nuclear states with K- bound
states
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 -         information concerning a
modification of the kaon mass and of the KN
interaction in the nuclear medium gt interesting
and important from the viewpoint of spontaneous
and explicit symmetry breaking of QCD
 -         information on a transition from the
hadronic phase to a quark-gluon phase gt changes
of vacuum properties of QCD and quark condensate
 -         kaon condensation in nuclear matter
gt implications on astrophysics neutron stars,
strange stars- nuclear dynamics under
extreme conditions (nuclear compressibility, etc)
could be investigated
Important impacts in fundamental physics
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From low-energy KN interactions to K-nuclear
bound states
to what extent does our present knowledge of
low-energy KN interactions support such
expectations (the hypothesis of narrow K-nuclear
states introduced by Akaishi and Yamazaki)? (W.
Weise, nucl-th/0507058) 1) the low-energy KN
scattering data 2) the kaonic hydrogen shift of
the ground state 3) the binding energy and
decay width of ?(1405), asserted to be an I0
quasi-bound state of KN. Rate of formation
and additional constraints 4) Kaonic helium
transitions
The pillars of the existence of narrow K-nuclear
states
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Future (expected) progress in the field1)
Kaonic Hydrogen and kaonic deuterium (SIDDHARTA
200 500 pb-1) -gt to eV gt I0 and I1 KN
scattering lengths2) Low-energy scattering A
new facility at DA?NE2 to study K- nuclear
clusters with a 4? detector, may include in its
scientific program a K scattering on
nucleons/nuclei to build up a high quality set of
data.3)   ?(1405) Precise KN measurements at
threshold (SIDDHARTA) will substantially improve
the knowledge of the sub-threshold KN dynamics
and contribute to clarify the nature of ?(1405).
More information can come from the measurement of
two-body branching ratios in K- absorption at
rest, which is precisely the kind of reactions to
be studied in the new facility at DA?NE2.
Specifically, one can investigate in-medium
corrections to the branching ratios in K-
absorption at rest and their effect on the
charged ? spectrum.
.
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4) Kaonic Helium SIDDHARTA (200 pb-1) - the
rate additional constraintsCrucial information
about the formation of a specific deeply bound
kaonic nuclear state (the K- 3He system) -gt
depends on the X ray transitions in the K- 4He
atom.There are three experiments which observed
kaonic helium atomic transitions from 3d to 2p
levels, giving an experimental average value for
the width G 55 34 eV. gt the formation
branching ratio turns out about 2 right now -gt
E570 at KEK.The theoretical widths are around
2-4 eV. Analogous discrepancy between
experiments and optical models calculations does
exists for the shifts. This is what is dubbed
the kaonic helium puzzle.Preliminary Monte
Carlo simulations, performed for the SIDDHARTA
setup with a gaseous 4He target show that a
measurement with a precision of eV can be
performed at DA?NE with about 200 pb-1 of
integrated luminosity. Similar estimations hold
for the 3He case. The capability to detect
kaonic helium X-rays transitions might turn out
extremely useful in implementing an X-ray trigger
to reduce the background in the measurement of
kaonic nuclear states by capture at rest on 4He
in a new dedicated facility at DA?NE2.
.
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Kaonic Hydrogen and deuterium
Deeply Bound Kaonic Nuclear States
L(1405)
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Production mechanisms of DBKNS

• 1) Stopped K- reactions on light nuclei, with
  ejection of a proton or a
• neutron as spectators
• 2)  In-flight K- reactions
• - Knock-out reactions (K-, N) where one
  nucleon is knocked out in the formation stage
• - (K-, p-) reactions in proton-rich systems
  to produce exotic bound nuclear states on unbound
  systems.
• 3) Protons (3.5 4.5 GeV) on a deuteron
  target for the production of Kpp detected in a
  4? detector.
• 4) The identification of clusters as
  residual fragments (K fragments) in heavy ion
  collisions via the invariant mass of their decay
  products.
• Identification and study of DBKNS
• - Formation -gt missing mass
• Decay -gt invariant mass
• -gt Spectroscopy!

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Current and future planned experiments

• FINUDA at DAFNE
• KEK E549
• E570
• J-PARC (LOI06 LOI10)
• GSI (FOPI)

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  Why DA?NE2 is a good place to study
kaonic nuclear clusters (1) The
future experiments in Japan (J-PARC) will produce
kaonic nuclear states only with K--induced
reactions in-flight (1 ? 2 GeV/c), either in
(K-, N) or in (K-, ?-) processes. The
alternative approach, followed at GSI, is
represented by proton-nucleus collisions at beam
energies close to the strangeness production
threshold and nucleus-nucleus collisionsIt
follows, that a dedicated facility at DA?NE2 can
become THE scientific pole for studying kaonic
nuclear states with K induced reaction at rest.
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Why DA?NE2 is a good place to study kaonic
nuclear clusters (2)The
salient features of DA?NE2 are-  Low-momentum
(127 MeV/c) medium intensity charged kaons ?
1200/s at L ? 1033 cm-2s-1-  Low momentum
spread (lt0.1) -  K? pairs produced in a
back-to-back topology-  hadronic background
intrinsically low differently from an
extracted beam.
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 How DA?NE2 characteristics can be exploited at
best for the study of strongly bound
kaonic nuclear states?1) possibility to use
either gaseous targets (as proven by DEAR) or
thin targets (as proven by FINUDA). 2) Reduced
neutron background generated by negative pion
absorption (E47) exactly in the area of interest.
The yield of these background neutrons depends on
the equivalent g/cm2 of the target, namely on
density and thickness, and on the materials put
around the target itself. 3) The back-to-back
topology which characterizes K- production, can
be used to trigger on (K-, K)-pairs, so
selecting K- induced events. 4) Another
trigger system might be implemented by taking
advantage of the X rays emitted in the decay of
the kaonic atom, created in the initial stage of
the process. 
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• Features of the experimental setup
• The complete study of the characteristic features
  of the kaonic bound nuclear systems requires
  knowledge of binding energy, level width and
  partial widths, angular momenta, isospin, sizes,
  densities, etc.
• This can be done by simultaneously observing the
  production stage of the K--clusters via missing
  mass spectroscopy, and their decay products since
  their momentum correlations contain information
  on the internal structure of the exotic system.
• It is therefore necessary to use a 4p dedicated
  detector capable of detecting all particles
  created in both the formation and decay of the
  K-clusters.

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• Features of the experimental setup
• Formation process
• Exotic nuclear states in light nuclei produced
  with (K-, N) reactions at rest will be observed
  by the energy distribution of the ejected protons
  and neutrons via the missing mass spectra of the
  (K-, p) and (K-, n) reactions.
• The setup should be capable to measure
• Outgoing protons up to 600 MeV/c
• Outgoing neutrons up to 600 MeV/c
• in a 4p acceptance detector, with good efficiency
  and resolution.

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Features of the exp. setup the decay process

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Monte Carlo simulation

n(500 MeV/c) Lnp ppnp-
L -gt p p- n lt 600 MeV/c p- lt 300 MeV/c

P(p-) GeV/c
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Features of the experimental
setup Decay process The exotic states are
expected to predominantly decay into final states
containing ? and S hyperons and protons,
neutrons, deuterons or larger systems of
nucleons. The most important feature of a
detector is therefore the reconstruction
capability for ? and S hyperons from the
invariant mass of their decay into nucleon ?
and/or g. This implies good particle
identification for these particles and their
decay products.


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Features of the experimental
setup Decay process From this data,
frame-invariant Dalitz plots can be constructed,
which are expected to reflect the size and
density of the initial exotic state. Special
attention must be paid to two-body correlations
in a Dalitz plane, which may lead to a fake
effect in an invariant mass spectrum ? p, which
might be confused with the genuine mass of an
exotic strange dibarion K-pp ? ? p if all the
three particles are not detected.


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Density distribution of K nuclear clusters
? by observing the momentum correlation in
their 3-body decay products (P. Kienle, Y.
Akaishi, T. Yamazaki to be published in Phys.
Lett. B)
K-ppn ? ? p n
JZ / Nov. 29, 2005
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• The detector satisfying all these features gt
• The KLOE detector
• Performance of the KLOE 4p detector
• fully checked and exploited in the numerous
  measurements done already by KLOE
• studies of processes with BR of lt 10-3 (10-6)
• acceptance 96
• DC sp/p 0.4
• Spatial resolution of vertices in DC 3 mm
• dE/dx capacity for particle ID implemented
• ECAL dE/Eg 5.7/E1/2
• st (54/E1/2 50) ps
• Ks-gtpp- at 0.8 MeV/c2
• p0 mass resolution to 2-3 (reconstruction)
• Resol. for n of 500 MeV/c 3

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AMADEUS Experimental programme
Measurements to be performed The most
fundamental system which we plan to study are the
kaonic dibaryon states of ppK- and npK-, which
are favorable produced using a 3He gas target in
3He(K-, n/p) reactions. Their masses including
their total width will be determined by neutron
and proton energy measurements respectively.
Exclusive measurements of their decays allow to
extract further information size/density,
angular momentum, ... A similar programme is
planned for kaonic 3-baryon states, populated in
reactions using a 4He gas target. Furthermore
we plan to extend these studies systematically
over a broad range of nuclear targets starting by
Li, B and Be.


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AMADEUS Experimental programme By observing
momentum correlation in the three-body decay
channel, such as pppK- ? ?pp or ppnK- ?
?pn, one will get information, using the
correlation pattern in the Dalitz plane, of the
size, density and the angular momentum of the
involved kaonic cluster. ? all decay products
have to be identified ? their 4-momenta have to
be determined


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The scientific programme of the nuclear
cluster facility will be discussed in dedicated
meetings and in the dedicated Workshop
Exotic hadronic atoms, deeply bound nuclear
states and antihydrogen present results and
future to be held at ECT (Trento), on
June 19-24, 2006 Organizers Catalina
Curceanu (Petrascu) LNF INFN, Frascati
(Italy) coordinator
Eberhard
Widmann , Stefan Meyer Institut für subatomare
Physik - Austrian
Academy of Sciences, Vienna (Austria)

Akaki Rusetsky, Univ. Bonn, Germany


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First actions towards AMADEUS


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• First actions towards AMADEUS
• KLOE calorimeter efficiency for neutrons
• Monte Carlo simple GEANT simulation gt to be
  continued
• gt e500MeV/c gt 20 (30)
• b) KLOESIDDHARTA tests on KLOE calorimeter
  prototype
• (long and short modules) on neutron beam
• n_TOF at CERN
• BTF at LNF (?)

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• First actions towards AMADEUS
• at n_TOF at CERN if available in 2006
• Neutrons from 1 eV to 150 MeV energy
• possibility to collimate the beam
• 10 100 MeV 106n/pulse
• dE/E (100 MeV) 2
• Prepare request to Research
• Board

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• First actions towards AMADEUS
• at BTF (LNF)
• Neutrons from photoproduction (-gt 800 MeV
  electrons)
• - Feasibility study (working group)

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• First actions towards AMADEUS
• AMADEUS integration in KLOE first drawing
• to be continued with
• setup integration gaseous and solid targets
• Physics ? Scientific program

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Search for anti-kaon clusters with KLOE
KLOE EMC
KLOE Drift Chamber
Possible setup for AMADEUS within
KLOE Cryogenic target Inner tracker Kaon trigger
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Preliminary design AMADEUS setup at KLOE

• a first draft of the interaction region

Kaon trigger
Cryogenic target cell
K
DEAR beam pipe
K-
Inner tracker
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 Preliminary extrapolationsAMADEUS on KLOE
setup confronted with KEK E471
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E471 Experiment Results 4He(K-stopped, n) and
4He(K-stopped, p) missing mass spectra
M. Iwasaki et al., nucl-ex/0310018 v2


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E471 features The results were obtained for a
total number of about 2 x 108 stopped negative
kaons inside the liquid helium target.
-        acceptance for detection of charged
particles 34 -        detection efficiency for
neutron 36 -        solid angle for the
neutron/proton detector 8. With these
conditions, the number of events in the missing
mass spectra of the two reactions, are -  about
450 events in the (K-, p) reaction for the S0
(3115) neutral tribaryon, with a
signal/background ratio about 1/10 -  about 120
events in the (K-, n) reaction for the S (3140)
charged tribaryon, with a signal/background
ration about 1/10 The formation ratios for the
considered reactions turned out to be of the
order of 10-3.


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• Extrapolation from KEK to DA?NE2
• more than 70 of kaons generated by ?decay can
  be stopped,
• with an optimized degrader, inside a gaseous
  helium target.
• For a yearly integrated luminosity of about 10
  fb-1, the total numbers of kaons generated in
  about 2 months (same time interval as at KEK)
  will be 2 x 109 and 1.4 x 109 will stop
  inside the target.
• For a dedicated 4? detector we assume the
  following figures of merit
• acceptance for the detection of charged
  particles 90
• detection efficiency for neutrons detector
  30
• solid angle for the neutron/proton detector
  90.
• Expected events in the case of a 4He target
• about 45000 in the (K-, p) reaction for the
  neutral tribaryon K-pnn
• - about 12000 in the (K-, n) reaction for the
  charged tribaryon K-ppn

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First actions towards AMADEUS
Pre-experiment PROPOSAL to KLOE The
DC of KLOE ? seen as an active target (4He)
where gt some K- stop gt DBKNS
DC

K-pnn
K-
p

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• First actions towards AMADEUS
• Pre-experiment PROPOSAL to KLOE
• A preliminary Monte Carlo simulation shows that
  with 2 fb-1 one might have due to K- stopped in
  the He gas of the DC
• gt 1500 events of
• -gt the BEST measurement in the world
• gt 500 events of
• AMADEUS group -gt willing to help KLOE in
• data analysis

K- 4He -gt p (K-pnn) p 550 MeV/c

K- 4He -gt n (K-ppn) n 510 MeV/c

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Even more
4He K- ? K-ppn n
K-ppn ? ? d
p ?-
K-ppn ? ? p n
p ?-
n
d
?-
n
p
?-
?-
p
p
energy MeV
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Formation of an international collaboration
The Proposal is presented by physicists
of the international collaboration
DEAR/SIDDHARTA, which are working on DA?NE since
1996 and where they will be still engaged for the
next three years. To the DEAR/SIDDHARTA
collaboration belong 11 institutions from 8
different countries. The interest raised in the
international community by kaonic atoms physics
at DA?NE involved, since the beginning, also
scientists from outside Europe, like Japan, USA
and Canada, which actively participated and are
participating to the experiments at DA?NE.

gthard core of an international collaboration
does already exist.

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Formation of an international collaboration
Other considerations support the strong appealing
of the new initiative and consequently a
potentially large interested community The
DA?NE2 with AMADEUS would represent the only
facility in the world where Kinduced reactions
at rest are studied. Moreover, after the GSI
merging into FAIR, Frascati would be the only
laboratory in Europe to go along this line of
research. The fact to become the European
counterpart with respect to the Japanese
programmes at J-PARC reinforces the plan to apply
to the Seventh Framework Programme of EU to
obtain a substantial economical support both for
developments of detectors and for the upgrading
of the actual machine.


Dec. 21-22, 2005Workshop on Antikaon Mediated
Bound Systems Doorway to Kaon Condensation in
Neutron Stars

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The scientific case of the study of deeply
bound kaonic nuclear states deals with one of
the most important, yet unsolved, problems in
hadron physics how the hadron masses and hadron
interaction change in the nuclear medium and what
is the structure of cold dense hadronic matter.
Conclusions (1)
After the shutdown of KEK in December 2005, two
facilities will be active in the field J-PARC in
Japan, and GSI (FOPI) in Europe. The first one
will produce kaonic nuclear clusters with
K--induced reactions in flight. GSI will follow,
before being absorbed in the new complex of
facilities FAIR, an alternative approach,
represented by nucleus-nucleus and proton-nucleon
collisions. DA?NE2 can become the
world-scientific pole to study the K- induced
processes at rest, which were indicated as the
more direct way to investigate the clusters in
nuclear matter.


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Conclusions (2)

• As far as the experimental setup is concerned,
  the 4p KLOE detector, implemented for AMADEUS
  program, operated in DAFNE2, satisfies the
  requirements to study the characteristic features
  of the K-nuclear clusters, which must consists
  both in observing the production stage of a
  K-nuclear clusters and detecting the decay
  products.
• First steps towards the realization
• Monte Carlo intensive simulations
• Measurement (KLOESIDDHARTA) of KLOE calorimeter
• for n-efficiency
• Feasibility of AMADEUS in KLOE
• Possibility to participate to KLOE2 new parts
• Spring 2006 -gt Letter of Intent

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From kaonic atoms to kaonic-nuclei Continuity and
innovation
An unique opportunity ONLY AT DAFNE2
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(No Transcript)
52

First experimental indications E471 Experiment
Results 4He(K-stopped, n) and 4He(K-stopped, p)
missing mass spectra
(M. Iwasaki et al., nucl-ex/0310018 v2)
S0(3115) M 3117 3.8-2.0(sys)/-0.9 (stat) Glt
21.6 MeV, B -194 MeV with respect to
K-pnn rest mass Predicted NOT to exist! (B20
MeV G100 MeV)

S(3140) M 3117 3.8-2.0(sys)/-2.3 (stat) Glt
21.6 MeV, B -169 MeV with respect to
K-ppn rest mass Predicted with B 110 MeV

M. Iwasaki et al., NIM A 473 (2001) 286
Y. Akaishi T. Yamazaki, Phys. Rev. C 65 (2002)
044005
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Monte Carlo simulation phase space

n(500 MeV/c) S-pp ppnp-
S- -gt n p- n lt 500 MeV/c p- lt 300 MeV/c

P(p-) GeV/c
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AMADEUS Experimental programme Is
based on precision spectroscopy studies of light
kaonic nuclei, as function of their baryon number
A and isospin T. In addition, heavier nuclear
targets will be studied. The first objective is
to determine the quantum numbers (spin, parity,
isospin) of all states, including excited ones,
and their energies. A precise measurement of
the energies of a T1 multiplet would give its
Coulomb energy difference (about 4 MeV) and thus
information on the size of kaonic nuclei. The
challenge of this programme is to reach the
necessary accuracy in the determination of the
mass differences of the multiplet.


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AMADEUS Experimental programme The study
of the spin-orbit interaction of the strange
tribaryon system (NNN)K, by measuring the
spin-orbit splitting (0p1/2 0p3/2) which is
predicted to be as large as 60 MeV (for small
size kaonic nuclei). Important information on
the structure of kaonic clusters is contained in
their total and partial decay widths. Until now,
only on upper limit of ? 21 MeV is known for a
kaonic tribaryon state and no information on
partial decay channels is available. For an
accurate measurement of the total width of kaonic
nuclei an energy resolution of MeV or better is
required.


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• As far as the signal/background ratio (S/B) is
  concerned, the neutrons produced by low-energy
  negative pion absorption, will be strongly
  reduced at DA?NE2, as previously shown.
• Moreover, the implementation of a (K, K-)-pair
  trigger and of an X-rays trigger from kaonic
  atoms decay, should improve S/B by more than a
  factor 2.

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