Upload
orinda
View
17
Download
0
Embed Size (px)
DESCRIPTION
Double antikaonic nuclear clusters in antiproton- 3 He annihilation at J-PARC. F.Sakuma, RIKEN. C. CURCEANU (INFN Frascati, Italy), M. IWASAKI (RIKEN, Japan), P. KIENLE (TUM, Germany), H. OHNISHI (RIKEN, Japan), M. TOKUDA (TITECH, Japan), K. TSUKADA (Tohoku-U, Japan), - PowerPoint PPT Presentation
Citation preview
Double antikaonic nuclear clusters in antiproton-3He annihilation
at J-PARC
F.Sakuma, RIKEN
1LEAP2011 @ TRIUMF, April 27 - May 1, 2011.
C. CURCEANU (INFN Frascati, Italy), M. IWASAKI (RIKEN, Japan), P. KIENLE (TUM, Germany), H. OHNISHI (RIKEN, Japan),
M. TOKUDA (TITECH, Japan), K. TSUKADA (Tohoku-U, Japan), E. WIDMANN (SMI, Austria), T. YAMAZAKI (RIKEN/U-Tokyo, Japan),
J. ZMESKAL (SMI, Austria)
2
(brief) Introduction of “Kaonic Nuclear Cluster”
Possibility of “Double-Kaonic Nuclear Cluster”
in pbar+A annihilation at restExperimental ApproachSummary
Outline
we will open new door to the high density matter physics, like the inside of neutron stars
Kaonic Nuclear Cluster (KNC)
3
T.Yamazaki, A.Dote, Y.Akiaishi, PLB587, 167 (2004).
Density [1/fm
3]
the density of the KNC is predicted to be high high densitydensity more than normal nuclear-density (0)
KKbarbarN interaction N interaction is clarified to be strongly attractive strongly attractive by Kaonic-atom experiments in 20th.
This leads the prediction of deeply-bound kaonic deeply-bound kaonic nuclear cluster (KNC)nuclear cluster (KNC), as many theorists pointed out.
4
Experimental Situation of KNC
FINUDA@DANE
We need more evidences in various channels!
DISTO@SATURENPRL, 94, 212303 (2005) PRL,104,132502 (2010)
stopped-K- + A ( + p) + X 2.85GeV-p + p ( + p) + K+
B.E. = 115MeV = 67MeV
B.E. = 103MeV = 118MeV
Because there is a discrepancy between THEORETICAL PREDICTIONS and EXPERIMENTAL OBSERVATIONS…
KK--ppppp?p?KK--ppppp?p?
5
J-PARC E15 Experiment
1GeV/cK- beam
p
p
n
NeutronToF Wall
K1.8BR Beam Line
neutron
Beam trajectory
CDS &target
SweepingMagnet
NeutronCounter
Beam LineSpectrometer
search for the K-pp using 3He(in-flight K-,n) reaction
flight length = 15m
Beam SweepingMagnet
CylindricalDetectorSystem
K-pp
Missing mass
Spectroscopy
via neutron Invariant
mass reconstructio
n
will start next year
6
Possibility of “Double-KaonicNuclear Cluster”
in pbar+A annihilation at rest
What will happen to put one more kaon in the kaonic nuclear cluster?
Why at rest?probability of multi-nucleon annihilation
(exotic B>0 annihilation) should be larger than in-flight reactions
7
Double-Kaonic Nuclear Cluster (DKNC)The double-kaonic nuclear clusters have been predicted theoretically.
How to produce the double-kaonic nuclear cluster?heavy ion collision(K-,K+) reactionpbarA annihilation
We use pbarA annihilation
PL,B587,167 (2004).
The double-kaonic clusters have much stronger binding energy and a much higher density than single ones.(AMD calc.)
ppn
ppnK-
ppnK-K-
p p K K K K
The elementary pbar-p annihilation reaction with double-strangeness production:
This reaction is forbidden for stopped pbar, because of a negative Q-value of 98MeV
the DKNC in pbarA annihilation?
if multi kaonic nuclear exists with deep bound energy, following pbar annihilation reactions will be possible!
98MeV
3 0 109MeVppKKp He K K K K pp B
8
e.g.
0K K
We can investigate the DKNCWe can investigate the DKNC with exclusive or semi-inclusive measurement with exclusive or semi-inclusive measurement
final state:the most energetic favored decay mode
p p
9
Related Topics
3 0
p He K K H
We can also search for H-dibaryon (H-resonance) by using invariant mass / missing mass.
E522@KEK-PS
PRC75 022201(R) (2007).
12 ,C K K X
The exclusive H search with The exclusive H search with stopped-pstopped-pbarbar beam has never beam has never
been done.been done.
3 0
+p
p He K K pp
Of course we can measure K-pp production with the dedicated
detector, simultaneously.
OBELIX@CERN-LEAR
NP, A789, 222 (2007).EPJ, A40, 11 (2009).
K-pp?4
p He K pp X
p
H?
Our experiment can check the Our experiment can check the OBELIX results of the KOBELIX results of the K--pp with a pp with a
dedicated spectrometerdedicated spectrometer
10
Past Experiments of Double-Strangeness Production in Stopped-pbar Annihilation
They did NOT observe any double-strangeness event in pbar - C, Ti, Ta, Pb annihilation (~80,000 events, p < 400 MeV/c)
Reaction Frequency (90% C.L.)
ppbarbarAA0000XX <4x10<4x10-4-4
pbarA0K-X <5x10-4
ppbarbarAAKK++KK++XX <5x10<5x10-4-4
pbarAHX <9x10-5
[Phys.Lett., B144, 27 (1984).]
There are NO results of the DKNC search, but several groups reported double-strangeness production in pbar+A annihilation
hydrogen bubble-chamber experiment @ BNLhydrogen bubble-chamber experiment @ BNL in association with the H-dibaryon search
11
Past Experiments of Double-Strangeness Production in Stopped-pbar Annihilation
experiment Channel # of events yield (x10-4)
DIANA@ITEPDIANA@ITEP[pbar+Xe]
PLB464, 323 (1999).
K+K+X 4 0.31+/-0.16
K+K0X 3 2.1+/-1.2
OBELIXOBELIX@CERN/LEAR@CERN/LEAR
[pbar+4He]NPA797, 109
(2007).
K+K+--ps 34+/-8 0.17+/-0.04
K+K+-+n- 36+/-6 2.71+/-0.47
K+K+-n 16+/-4 1.21+/-0.29
K+K+K-nn 4+/-2 0.28+/-0.14
Although observed statistics are very small,their results have indicated a high yield of ~10-4
12
Experimental Approach
The double-strangeness production yield of ~10-4 makes it possible to explore the exotic systems.
13
Experimental Strategy
I.I. investigation of investigation of “double-strangeness “double-strangeness production”production” in p in pbarbar++33He annihilation at rest, He annihilation at rest, with high statistics datawith high statistics data
II.II. search for search for “double-kaonic nuclear cluster”“double-kaonic nuclear cluster” in pin pbarbar++33He annihilation at restHe annihilation at rest
Current situation of the double-strangeness production in pbar+A (A>2) annihilation at rest:NO results using a dedicated spectrometer except for bubble chamber experiments.NO results with high-statistics measurement.
3
3 0
p He K K
p He K K
3 0
+
p He K K K K pp
K1.8BR Beam LineCDS &
targetBeam Line
Spectrometer
14
SetupWe will perform the proposed experimentWe will perform the proposed experiment
at J-PARC K1.8BR beam lineat J-PARC K1.8BR beam line
~2800 mass =3.5+/-0.1MeV/c2
key pointskey pointshigh intensity pbar beamlow mass material detectorwide acceptance detector
reconstructed p- inv. mass in commissioning run (2010, Oct.)
0.9GeV-K + A + X
15
pbar Beam @ J-PARC K1.8BR
pbar stopping-rate
50kW, 30GeV6.0degreesNi-target
pbar production yield witha pbar CS parameterization
250 stopped p250 stopped pbarbar/spill/spill@ 0.7GeV/c, l@ 0.7GeV/c, ldegraderdegrader3cm3cm
Incident Beammomentum bite : +/-2.5% (flat)incident beam distribution : idealDetectorsTungsten Degrader : =19.25g/cm3
Plastic Scintillator : l=1cm, =1.032g/cm3
Liquid He3 target : =7cm, l=12cm, =0.080g/cm3
pbar stopping-rate evaluation by GEANT4
6.5x103/spill/3.5s @ 0.7GeV/c
16
Trigger Scheme
pbar+3He charged particle multiplicity at restCERN LEAR, streamer chamber exp. NPA518,683 (1990).
Nc Branch (%)
1 5.14 +/- 0.04
3 39.38 +/- 0.88
5 48.22 +/- 0.91
7 7.06 +/- 0.46
9 0.19 +/- 0.08
<Nc> 4.16 +/- 0.06
expected stopped-pbar yield = 250/spill @ 50kW
All events with a scintillator hit can be accumulatedAll events with a scintillator hit can be accumulated
expectedK-K-pp event
17
Experimental Strategy
I.I. investigation of investigation of “double-strangeness “double-strangeness production”production” in p in pbarbar++33He annihilation at restHe annihilation at rest
II.II. search for search for “double-kaonic nuclear cluster”“double-kaonic nuclear cluster” in pin pbarbar++33He annihilation at restHe annihilation at rest
present situation of the double-strangeness production in pbar+A (A>2) annihilation at rest:NO results with a dedicated spectrometer and high intensity beam except for bubble chamber experiments.high-statistics measurement is NOT performed!
3 0
+
p He K K K K pp
3
3 0
p He K K
p He K K
18
Double-Strangeness Measurement3
3 0
p He K K
p He K K
K+K+- channel K+K0channelK+K+
detection 2.4 x 10-1 detection 4.1 x 10-2
K+K+detection 4.4 x 10-2 K+
detection 2.1 x 10-2
K+K+-
detection 2.8 x 10-2 K+K0
detection 2.9 x 10-3CDS @ K1.8BRCDS @ K1.8BR
evaluated using GEANT4 toolkitMany-body decay are considered to be isotropic decay.branching ratios of K0K0
S/K0S/p are included.
acceptance is defined by CDC
acceptances of Kacceptances of K++KK++ and and
19
Double-Strangeness Measurement (Cont’d)
30kW, for 2weeksK+K+ event 750 event 130
if we assumethe double-strangeness production-yield to be 10-4 / stopped-pbar
as reported by the OBELIX and DIANA groups:
expected yieldexpected yield
* The following are includedduty factor of the accelerator and apparatus : 21h/24hDAQ and analysis eff. : 0.7
sensitivitysensitivity 30kW, 2weeks30kW, 6weeks
30kW, 1week
50kW, 6weeks
100kW, 6weeks
OBELIX/
DIANA
number of proton on targetpr
oduc
tion-
yiel
d (/
stop
ped-
pbar )sensitivity to 100 double-
strangeness events (~10) detection is evaluated by
the MC.
1.E-04
20
Experimental Strategy
I.I. investigation of investigation of “double-strangeness “double-strangeness production”production” in p in pbarbar++33He annihilation at restHe annihilation at rest
II.II. search for search for “double-kaonic nuclear cluster”“double-kaonic nuclear cluster” in pin pbarbar++33He annihilation at restHe annihilation at rest
present situation of the double-strangeness production in pbar+A (A>2) annihilation at rest:NO results with a dedicated spectrometer and high intensity beam except for bubble chamber experiments.high-statistics measurement is NOT performed!
3 0
+
p He K K K K pp
3
3 0
p He K K
p He K K
21
Procedure of the K-K-pp Search
methods of the measuremtmethods of the measuremt(semi-inclusive) K0K+ missing-mass w/ -tag(inclusive) invariant mass(exclusive) K0K+ measurement
3 0
+
p He K K K K pp
--- K0K+ w/ -tag --- --- K0K+
K-K-pp binding energy
evaluated using GEANT4 toolkit (K-K-pp) = 100 MeVisotropic decaybranching ratios of K0K0
S/K0S/p
are included.
acceptanceacceptance
22
Backgrounds(semi-inclusive) K(semi-inclusive) K00KK++ missing-mass w/ missing-mass w/ -tag-tag
stopped-pbar + 3He K0 + K+ + K-K-pp
stopped-pbar + 3He K0 + K+ + + stopped-pbar + 3He K0 + K+ + + + 0 …
stopped-pbar + 3He K0 + K+ + K0 + 0 + (n)stopped-pbar + 3He K0 + K+ + 0 + (n) …
3N annihilation
2N annihilation
signal
*each spectrum is obtained with the same production yield
K0K+ missing-mass
23
Backgrounds (Cont’d)(inclusive) (inclusive) invariant mass invariant mass
stopped-pbar + 3He K0S + K+ + K-K-pp
+ stopped-pbar + 3He K0
S + K+ + K-K-pp0 + 0
stopped-pbar + 3He K0S + K+ + K-K-pp
0 + 0 + 0 …
missing 2
missing 2+
B.E = 200 MeV = 100 MeV
signal
*each spectrum is obtained with the same production yield
invariant mass
production yield:•K-K-pp bound-state = ?•(3N) K-K- phase-space = 5x10-5
•(3N) K+K0000 phase-space = 5x10-5
•(2N) K+K0K00(n) phase-space = 3x10-4
24
Expected Yield
total yield : upper limit of pbarAKKX, 5x10-4
3N : 20% of yield, and 3N:2N = 1:3
K-K-pp yield : parameter
Sensitivity to the K-K-pp observation Sensitivity to the K-K-pp observation is estimated using the MCis estimated using the MC
non-mesonic : mesonic = 1 : 1
branching ratio:•BR(K-K-pp) = 0.25•BR(K-K-pp00 = 0.25•BR(K-K-pp00 0) = 0.5
assumptions
25
Sensitivity to the K-K-pp signal (Exclusive)significance [=S/sqrt(S+B)] is obtained
in exclusive missing-mass spectra
--- BKK = 120 MeV--- BKK = 150 MeV--- BKK = 200 MeV
30kW, 6weeks
100kW, 6weeks
270kW, 6weeks
50kW,6weeks
number of proton on target
3 s
igni
fican
ce o
fK- K
- pp
prod
uctio
n yi
eld
(/st
oppe
d-pba
r )
26
Expected Spectra @ 50kW, 6weeks3 0 ( )p He K K X
# of K-K-pp = 32
K+K0 missing mass (2K2)
0 K K X
# of K-K-pp = 357
invariant mass
0 ( )K K X
invariant mass
# of K-K-pp = 15
0 K K X
K+K0 missing mass
# of K-K-pp = 208
assumption in the figures:K-K-pp production yield
= 10-4/stopped-pbar
B.E. = 200 MeV = 100 MeV
The signal can be discriminated from the other backgrounds in the exclusive K+K0 missing
mass spectrum.
27
Summary
We will search for Double-Kaonic Nuclear Double-Kaonic Nuclear Cluster (DKNC) by pCluster (DKNC) by pbarbar + + 33He annihilation at restHe annihilation at rest, using the pbar + 3He K+ + K0 + X (X = K-K-pp) channel @ J-PARC K1.8BR beam line.
In preparation for the DKNC search, double-double-strangeness productionstrangeness production measurement will be conducted as a first step.
We are now improving this experimental idea toward the proposal submission to J-PARCproposal submission to J-PARC.
28
ScheduleYear (JFY) K1.8BR
2009 beam-tune2010 beam-tune2011 recovery2012 E17/E152013 E15/E312014 E15/E312015 here?
The proposed experiment will start in around JFY2015???