1. the physics case 2. present status 3. hypersystems in pp interactions 4. the experiment future...
TRANSCRIPT
1. The Physics Case2. Present Status3. Hypersystems in pp Interactions4. The Experiment
Future Experiments on Hypernuclei and
Hyperatoms
_
1. The Physics Case
baryons tagged with a strange quark as a probe of the nuclear structurenuclei as a femto-laboratory for strange baryons
Two Sides of a Coin
mesonic decay of hypernuclei
mesonic decay of hypernuclei
w
N
suppressed by Pauli blocking
pF270MeV/c
w
N
pN100MeV/c
free decayfree decay
0n
+38MeV ( )
+41MeV ( )
2
6
6
4
36
%
%
3ps
p
non-mesonic decay
of hypernuclei
non-mesonic decay
of hypernuclei
w
N
s
N
N
+176MeV
+176MeVnn
p
n
p n
To use nuclei as a QCD-laboratory we have to understand the laboratory
s=1: -, -hypernucleinuclear structure, new symmetries
the presence of a hyperon may modify the size, shape... of nuclei new specific symmetries
Y-N interactionstrange baryons in nuclei weak decay
s=2: -atoms, -, -hypernucleinuclear structurebaryon-baryon interaction in SU(3)f
H-dibaryon
s=3: -atom, (-,-, -hypernuclei ?)quadrupole moment of the
Hypernuclei provide a link between nuclear physics and QCD
Strange Baryons in Nuclear Systems
W
su dusd dd
meson vs. gluon/quark exchange
meson vs. gluon/quark exchange
Weak baryon-baryon interaction non-mesonic weak decay of hypernuclei explore the baryon-baryon weak interaction
N-N scatteringN-N scattering
w
N
N
s
N
N
w
N
s
N
N
S=0 S=1
NN NNN N
only parity violating part of weak interactionparity-conserving part masked by strong interaction
only parity violating part of weak interactionparity-conserving part masked by strong interaction
parity violating and parity-conserving part of weak, strangeness changing, interactionq~400 MeV/c probes short distances
parity violating and parity-conserving part of weak, strangeness changing, interactionq~400 MeV/c probes short distances
T. Sakai, K. Shimizu, K. Yazaki Prog.Theor.Phys.Suppl. 137 (2000) 121-145
H-Particle R.L. Jaffe (1977)
free coalescencet ~ 10-23s
nuclear breeder
t ~ 10-10s
neutron stars
Nuclei as Femto-Laboratory
H-particle in a nucleus free H (see e.g. T. Yamada, NP A691 (2001) 250c; (3q)+(3q) quark cluster model )
free H-dibaryonH-dibaryon in 10
YYBe
B=12.2 MeV B=24.0 MeV
S=-2 Nuclei and H-dibaryon States
Formation of an H-particle in nuclei may modify levels in -nuclei
Contributions to intrinsic quadrupole moment of baryonsOne-gluon exchangeMeson exchange
J=1/2 baryons have no spectroscopic quadrupole moment
- Baryon:J=3/2long mean lifetime 0.82·10-10 sonly one-gluon contributions to quadrupole moment(A.J. Buchmann Z. Naturforsch. 52 (1997) 877-940)
3 2 2( )(3 )iQ d r r z r 3 2 2( )(3 )iQ d r r z r
s
ss
1/ 221/ 2
(3 ( 1)) 0z
Js z J
Q J J J 1/ 221/ 2
(3 ( 1)) 0z
Js z J
Q J J J
Fundamental Properties of Baryons
The quadrupole moment is an unique testcase for the quark-quark interaction
hyperfine splitting in -atom electric quadrupole moment of
prediction Q= (0 - 3.1) 10-2 fm2
E(n=11, l=10 n=10, l=9) ~ 515 keVEQ ~ few keV for Pb
spin-orbit Els ~ (Z)4 l·m
quadrupole EQ ~ (Z)4Qm3
spin-orbit Els ~ (Z)4 l·m
quadrupole EQ ~ (Z)4Qm3
Q= +0.02 fm2
Q= - 0.02 fm2
A very Strange Atom
R.M. Sternheimer, M. Goldhaber PRA 8, 2207 (1973)
2. Present Status
strangeness deposition (stopped K-,-) FINUDA@DANEtagged kaon „beam“low momentum (T=16MeV)low backgroundalso (stopped K-,+) neutron rich nuclei
strangeness production (+, K+) (-, K0) BNL, KEK, (GSI?)
pBEAM 1 GeV/c
high beam intensitylow cross section (1-10 mb/sr)q > 300 MeV/c large p, L
strangeness exchange (K_
, )(K_
, ) BNL, KEK, J-PARClow beam intensitylarger cross section (100 mb/sr)magic momentum low p, L
(e,e´K+) , (,K+) TJNAF, MAMI-Cspin-flip amplitude unnatural parity statesnew nuclei (p : 10
Be)
polarised beamsub-MeV resolution possible (0.3 MeV) for particle unstable states
substitutional state
non-substitutional state
Single Hypernuclei
( 1)A Ae Z e K Z ( 1)A Ae Z e K Z
stoppA
dA
e
KK
Z ZK
e e
stoppA
dA
e
KK
Z ZK
e e
Tamura et al.
Neutron number
16Λ O 18
Λ O14Λ N 15
Λ N12Λ C 13
Λ C 14Λ C
9ΛB 10
Λ B 11Λ B 12
Λ B7ΛBe 8
ΛBe 9ΛBe10
Λ Be6ΛLi 7
ΛLi 8ΛLi 9
ΛLi4ΛHe 5
ΛHe6ΛHe 7
ΛHe 8ΛHe
4ΛH3
ΛH
1 2 3 4 5 6 7 8 9
4
8
7
6
3
5
2
1
10
9
Pro
ton
nu
mb
er
Status of Single Hypernuclei
high resolution -spectroscopy
with germanium detectors
7 0.5 2 40.4
6 2 4
( 2; : 5 / 2 1/ 2 ) 3.6 0.5 1
( 2; : 3 1 ) 10.9 0.9 3
B E Li e fm
B E Li e fm
B(E2)~R4
shrinkage of 6Li core by ~20%
high resolution -spectroscopy is crucial to understand the structure of hypernculei
KEK, BNL
Multi-Hypernuclei are terra incognita, but they exist !
1963: Danysz et al. 10Be
1966: Prowse 6He
1991: KEK-E176 13B (or 10Be)
2001: AGS-E906 4H (~15);
no binding energies
2001: KEK-E373 6He
(Nagara)
“ 10Be
(Demachi-Yanagi)
NAGARA
6- 12 4
6 5
ΛΛ
-ΛΛ Λ
Ξ + C + He+t
He He+ π
He
p+
H. Takahashi et al., PRL 87, 212502-1 (2001)
Double Hypernuclei
Interpreting B as bond energy one has to consider e.g.
dynamical change of the core nucleusN spin-spin interaction for non-zero spin of coreexcited states possible
if- or intermediate -nuclei are produced in excited statesQ-value difficult to determine (particularly for heavy nuclei)nuclear fragments difficult to identify with usual emulsion technique
new concept required -spectroscopy!
1
1
( ) ( ) ( )
( ) ( ) ( )
A A A
A A A
B Z B Z B Z
B Z B Z B Z
What is known?
6
6 0.18 0.180.11 0.11
10
10
13
Hyperkern ( ) ( )
10.9 0.5 4.7 0.6 Prowse (1966)
7.25 0.19 1.01 0.20 KEK-E373 (2001)
17.7 0.4 4.3 0.4 Danysz (1963)
8.5 0.7 4.9 0.7 KEK-E176 (1991)
27.6 0.7 4.8
B MeV B MeV
He
He
Be
Be
B
10 0.35
0.21
0.7 KEK-E176 (1991)
12.33 KEK-E373 (2001, unpublished)Be
same event
same event
3. Hypersystems in pp Interactions_
-atoms: x-raysconversion
-(dss) p(uud) (uds) (uds)Q = 28 MeV
Conversion probability approximatly 5-10%
Y. Hirata, J. Randrup et al.,
- capture
_
(Kaidalov & Volkovitsky)
quark-gluon string model
s
ud
s
dd
s
ds
s
ss
0
Use pp Interaction to produce a hyperon “beam” (t~10-10 s) which is tagged by the antihyperon or its decay products
_
General Idea
- capture:
- p + 28 MeV-
3 GeV/c
Kaons_
trigger
p_
2. Slowing down and capture
of insecondary
target nucleus
2. Slowing down and capture
of insecondary
target nucleus
1.Hyperon-
antihyperonproductionat threshold
1.Hyperon-
antihyperonproductionat threshold
+23MeV
3. -spectroskopy
with Ge-detectors
3. -spectroskopy
with Ge-detectors
Production of Double Hypernuclei
20000 stopped -K- beam, diamond target
neutron detector arrays
(--,12C) 12B + nBNL-AGS E885
few tens 2 decays of 4
HK- beam lineCylindrical Detector
System2 decaysBNL-AGS
E906
Captured - per day
beam/ targetdevicereactionfacility
several hundreds stopped -
(K-,K+)emulsion(K-,K+)KEK-PS E373
vertex detector + spectrometer
vertex detector
spectrometer, =30 msr
device
3000 „golden events“
~ 300000 KK trigger
(incl. trigger)
=2·1032, thin target,production vertex decay vertex
p p GSI-HESR
2000106 stopped p per sec
p p K*K*
K*N Kcold anti-protons
<70008·106/sec5 cm 12C
(K-,K+)JHF
statusbeam/ targetreactionexperiment
Competition
¯
¯
¯
¯
¯¯
Expected Count Rate
Ingredients (golden events)luminosity 2·1032 cm-2s-1 +- cross section 2mb for pp 700 Hz p(100-500 MeV/c) p500 0.0005 + reconstruction probability 0.5 stopping and capture probability pCAP 0.20 total captured - 3000 / day
- to nucleus conversion probability p 0.05 total hyper nucleus production 4500 / month
gamma emission/event, p 0.5
-ray peak efficiency pGE 0.1
~7/day „golden“ -ray events (+ trigger) ~ 700/day with KK trigger
high resolution -spectroscopy of double hypernuclei will be feasible
- capture:
- p + 28 MeV-
5.5 GeV/c
Kaons_
trigger
p_
2. Slow down
and capture of in
secondary target nucleus
2. Slow down
and capture of in
secondary target nucleus
1.Hyperon-
antihyperonproductionat threshold
1.Hyperon-
antihyperonproductionat threshold
+203MeV
3. -spectroskopy
with Ge-detectors
3. -spectroskopy
with Ge-detectors
Production of -Atoms
( ) 1( ) 20
atoms by produktion (~35/sec)hyperfine splitting in -atom
electric quadrupole moment of
prediction Q= (0 - 3.1) 10-2 fm2
E(n=11, l=10 n=10, l=9) ~ 515 keVEQ ~ few keV for Pb
taking production rate, stopping probability, capture probability and detection probability into account we expect
-
spin-orbit Els ~ (Z)4 l·m
quadrupole EQ ~ (Z)4Qm3
spin-orbit Els ~ (Z)4 l·m
quadrupole EQ ~ (Z)4Qm3
Q= +0.02 fm2
Q= - 0.02 fm2
~10 detected -transitions per daywith high resolution -spectroscopy feasible
A very strange Atom
R.M. Sternheimer, M. Goldhaber PRA 8, 2207 (1973)
Count rate estimate needs more detailed studies!
4. The Experiment
The PANDA Detector
hermetic (4)high ratePID (, e, , , K, p)trigger (e, , K, D, ) compact (€)modular
Elektronenkühler
InjektionKicker Septum
Solid state-micro-trackerthickness ~ 3 cm
High rate germanium detector
Summary
Hypersystems provide a link between nuclear physics and QCD
They allow to study basic properties of strongly interacting systems
These unique experiments will be feasible at the GSI-HESR