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Hypernuclei: A quick introduction
Electroproduction of hypernuclei
E94-107 experiment UPDATE
Experimental equipment and setup
Analysis results of 2004 run on 12C and 9Be
Preliminary results of 2005 run on 16O
Conclusions
Mauro Iodice – e94107 update – Hall A Collaboration Meeting, JLAB, Dec 6 2005
A.Acha, H.Breuer, C.C.Chang, E.Cisbani, F.Cusanno, C.J.DeJager, R. De Leo,
R.Feuerbach, S.Frullani, F.Garibaldi*, D.Higinbotham, M.Iodice, L.Lagamba,
J.LeRose, P.Markowitz, S.Marrone, R.Michaels, Y.Qiang, B.Reitz, G.M.Urciuoli,
B.Wojtsekhowski
And the Hall A Collaboration
JLAB Hall A E94107
COLLABORATION
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
HYPERNUCLEI …what they are
Hypernuclei are bound states of nucleons with a strange baryon (Lambda
hyperon). A hypernucleus is a “laboratory” to study nucleon-hyperon
interaction (-N interaction).
Extension of physics on N-N interaction to system with S0
Internal nuclear shell are not Pauli-blocked for hyperons.
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
HYPERNUCLEI and ASTROPHYSICS
Strange baryons may appear in neutral -stable matter through process like:
€
n + e− → Σ− + ν e
The presence of strange baryons in neutron stars strongly affect their
properties. Example: mass-central
density relation for a non-rotating (left) and a rotating (right) star
The effect strongly depends upon the poorly known interactions of strange baryons
More data needed to constrain theoretical models.
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Hypernuclei - historical background - experimental techniques
To commemorate their discovery the above postcard was issued by the Polish Post in May 1993
1953 : discovery of first hypernucleus by Danysz and Pniewskiwhile studying cosmic radiation with emulsion techniques
1962 : The first double Hypernucleus wasdiscovered in a nuclear emulsionirradiated by a beam of K- mesons
at CERN
The first observation of a hypernucleus
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
1953 1970 : hypernuclear identification with visualizing techniquesemulsions, bubble chambers
1970 Now : Spectrometers at accelerators:
CERN (up to 1980)
BNL : (K-, -) and (K+, +) production methods
KEK : (K-, -) and (K+, +) production methods
> 2000 : Stopped kaons at DANE (FINUDA) : (K-stop, -)
> 2000 : The new electromagnetic way :
HYPERNUCLEAR production with
ELECTRON BEAM at JLAB
Elementary reactionon neutron :
€
K− + n → π − + Λ
€
+ + n → K + + Λ
€
12C → 12CΛ
e.g.
Elementary reactionon proton :
€
e + p → ′ e + K + + Λ
€
12C → 12BΛ
e.g.
Hypernuclei - historical background - experimental techniques
Production of MIRROR hypernuclei
: I=0, q=0 n = pSpectroscopy of mirror hypernuclei reveal n ≠ p 0 mixing and N-N coupling
Present status of Hypernuclear Spectroscopy
O. Hashimoto and H. Tamura, Prog. Part. Nucl. Phys, in press.
(e,e’K+)
€
16N
This exp. E94-107
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
What do we learn from hypernuclear spectroscopy Hypernuclei and the -N interaction
“weak coupling model”
(parent nucleus) ( hyperon) (doublet state)
€
JA−1 + Λ(s − shell) → JHyp = JA−1 ± 12
€
VΛN = V0(r) + Vσ (r)r s Λ ⋅
r s N + VΛ (r)
r l ΛN ⋅
r s Λ + VN (r)
r l ΛN ⋅
r s N + VT (r)S12
S SNT
€
J + 12
€
J
€
J − 12
(A-1)A
SN
, S , T
Split by N spindependent interaction
HypernuclearFine Structure
Low-lying levels of Hypernuclei
Each of the 5 radial integral (V, , S, SN, T) can be phenomenologically determined from the low lying level structure of p-shell hypernuclei
V
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Electroproduction of hypernuclei
by the reaction:
E94-107 Experiment:“High Resolution 1p Shell Hypernuclear Spectroscopy”(spokespersons: F. Garibaldi, S. Frullani, J. Le Rose, P. Markowitz, T. Saito – Hall A Coll.)
€
e +AZ → ′ e + K + + A
Z −1( )Λ
€
e +AZ → ′ e + K + + A
Z −1( )Λ
Hypernucleus
K+
ee’
p
AZ(e,e’K)A(Z-1)HRSe at 6˚
HRSk at 6˚ e beam~4 GeV
Nuclear targets and resulting hypernuclei:
9Be 9Li(spin doublets, information on s-s term of -N interaction potential)
12C 12B(comparison with previous data: better understanding of results with hadron probes
and E89-009 in Hall C at Jefferson Lab; clear identification of core excited states)
16O 16N(details of the hyper. spectrum also depends on single particle spin-orbit splitting )
Spin flip states
p Production of mirror nuclei / n rich hypernuclei
High energy resolution
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Detection at very forward angle to obtain reasonable counting rate
(increase photon flux) Septum magnets at 6°
Excellent ParticleIDentification system for unambiguous kaon selection
over a large background of p, RICH
Accurate monitoring of many parameters over a long period of data taking : Beam spread (SLI, OTR) and absolute energy, spectrometers NMR, BPMs, …
Excellent energy resolution Best performance for beam and HRS+Septa
with accurate optics calibrations
Experimental requirements :
1. E/E : 2.5 x 10-5
2. P/P (HRS + septum) ~ 10-4
3. Straggling, energy loss…
≤ 600 keV
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Last year e94107 experiment took data in two separate periods. Data have been collected on solid targets. The second part of the experiment took data in June 2005 in Hall A using the waterfall target
January 2004 12C target
April 2004 12C target and May 2004 9Be
June 2005 Waterfall target for hypernuclear state production on 16O and (as a byproduct) on the elementary process on Hydrogen
Data taking, Kinematics, Counting rates :
Ebeam = 4.016 — 3.777 — 3.656 GeV
Pe= 1.80 — 1.56 — 1.44 GeV/c
Pk= 1.96 GeV/c
e = K = 6°
= E 2.2 GeV – Q2 = 0.079 (GeV/c)2
Beam current : 100 A Target thickness : ~100 mg/cm2
Counting Rates ~ 0.1 – 10 counts/peak/hour
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
SEPTUM magnets in Hall A: new optics DB for the D+QQDQ system
QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
FWHM = 1.1x10-4
FWHM = 2.2x10-4
NEW DB “2005”OLD DB “2004”
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
KAON Id Requirements physics case
Process Rates
signal Bound states (e,e’K)
10-4 – 10-2
accidentals (e,e’)(e,)
(e,e’)(e,p)(e,e’)(e,k)
1001000.1
Forward angles higher background of and p
TOF and 2 Threshold Cherenkov NOT sufficient for
unambiguous kaon identification
RICH DETECTOR
Signal Vs. Background
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
RICH detector –C6F14/CsI proximity focusing RICH
Chϑ“MIP”
Performances: Np.e. # of detected photons (p.e.)and (angular resolution)
..
..
ep
ep
Nc
ϑϑ
=
Cherenkov angle resolution
Separation Power
cϑϑϑ n12 =−
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Rich Performance ‘key parameters’:
mrad c
5≈ϑAngular resolution:
Npe /p ratio:
66.01
122
22
=−−
=nn
NN P
clus
Pclus
Npe for and p
Cherenkov angle for
Cherenkov average angle (rad)
Nclusters
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Rich – PID – Effect of ‘Kaon selection’:
P
K
Coincidence Time selecting kaons on Aerogels and on RICH:
AERO K AERO K && RICH K
Pion rejection factor ~ 1000
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Rich – PID – Effect of ‘Kaon selection’:
PK
Coincidence Time selecting kaons on Aerogels and on RICH:
AERO K AERO K && RICH K
GREATLY improved AEROGEL performance!
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Shell model excitation levels for 12B
dependence on the N potential - different set of potential params.
x 0p
x 0s
11C energy spectrum
J=1-, 2- doublet
x 0sJ=1-
J=2-
J=2+, 3+
J=1/2-
E=~2 MeV
J=3/2-
E=0.0 MeV
J=3/2-
E=~5 MeV
J=5/2-
E=~4.5 MeV
x 0s
12B energy spectrum
J=1-
J=2-
J=2+, 3+
J=1-
J=2-
J=2+, 3+
YNG potential “Canonical” “Standard”
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Monte Carlo simulation of 12Bexcitation-energy levels produced on 12C target
12C(e,e’K)12B
a cb d
( )( )
)())((3
(Tensor) )(
orbitspin )(
orbitspin )(
spin)(spin )(
(central)V )(
12
12
0N
ΛΛ
Λ
ΛΛΛ
Λσ
Λ
σ⋅σ−⋅σ⋅σ=
+
−σ⋅+
−σ⋅+
−Δσ⋅σ+
=
NN
T
NNNSO
NSO
N
rrS
TSrV
SrV
SrV
rV
rVV
rr
l
l
Absolute and relative positions of “resolved” levels a,b,c,d, may provide information on parameters of interaction potential and its terms (spin-spin, spin-orbit, tensor, …)
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
9Be(e,e’K)9Li
a c db
( )( )
)())((3
(Tensor))(
orbitspin)(
orbitspin)(
spin)(spin)(
(central)V)(
12
12
0N
ΛΛ
Λ
ΛΛΛ
Λσ
Λ
σ⋅σ−⋅σ⋅σ=
+
−σ⋅+
−σ⋅+
−Δσ⋅σ+
=
NN
T
NNNSO
NSO
N
rrS
TSrV
SlrV
SlrV
rV
rVV
rr
Monte Carlo simulation of 9Liexcitation-energy levels
Produced on 9Be target Excitation-energy levels of 9Lihypernucleus, especially from the first-doublet levels a and b,
would provide important information on S and T terms of the N interaction. Separation of c and d doublets may provide information on the spin-orbit term SN
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Theoretical model for 16Nexcitation-energy on 16O target
The structure of underlying nucleus 15N is dominated by:
(i) J=1/2-proton-hole state in 0p1/2 shell - ground state
(ii) J=3/2- proton-hole state in 0p3/2 shell - Excited states at Ex = 6.32 MeV
Details of the hypernuclear spectrum at Ex ~ 17-20 MeV depends not only on -N residual interaction but also on the single particle spin-orbit splitting (difference in energy of 0p3/2 and 0p1/2 states)
Coupling of
p1/2 and p3/2
16O(e,e’K)16N
15N energy spectrum 16N energy spectrum
Results from last year run on 12C target
Analysis of the reaction 12C(e,e’K)12B
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Results on 12C target – Hypernuclear Spectrum of 12B
12C(e,e’K)12B12C(e,e’K)12B
< 1 MeV FWHM
Missing energy (MeV)
g.s.
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
As obtained with the old optics DB. The new one does not improve the resolution … still under analysis/investigation
Aerogel Kaon selection
RICH Kaon selection
12C(e,e’K)12B12C(e,e’K)12B
€
Signal
Bckgnd= 2.5
€
Signal
Bckgnd> 7
Analysis on 12B spectrum : Aerogel vs. RICH K-selection
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Analysis on 12B spectrum : FIT to the data
Gaussian fit systematically underestimateThe peaks try with different shapes :
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
JLAB Hall A E94-107: preliminary comparison with theory for 12Bhypernucleus
Missing energy (MeV)
Cou
nts
/ 2
00 k
eV
12C(e,e’K)12B12C(e,e’K)12B
Two theoretical curves (blue and red), two different model for the elementary K- production on proton.
Same hypernuclear wave-function (by Miloslav Sotona).
Red line: Bennhold-Mart (K MAID)
Blue line: Sagay Saclay-Lyon (SLA).
Curves are normalized on g.s. peak.
Two theoretical curves (blue and red), two different model for the elementary K- production on proton.
Same hypernuclear wave-function (by Miloslav Sotona).
Red line: Bennhold-Mart (K MAID)
Blue line: Sagay Saclay-Lyon (SLA).
Curves are normalized on g.s. peak.
The relative intensity of first excited-core peak at 2.6 MeV and strongly populated p-Lambda peak at 11 MeV would be better described by K MAID model than SLA.
The relative intensity of first excited-core peak at 2.6 MeV and strongly populated p-Lambda peak at 11 MeV would be better described by K MAID model than SLA.
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
JLAB Hall A E94-107: preliminary comparison with theory for 12Bhypernucleus
Missing energy (MeV)
Cou
nts
/ 2
00 k
eV 12C(e,e’K)12B
12C(e,e’K)12BTwo theoretical curves (blue and red), two different model for the elementary K- production on proton.
Same hypernuclear wave-function (by Miloslav Sotona).
Red line: Bennhold-Mart (K MAID)
Blue line: Sagay Saclay-Lyon (SLA).
Curves are normalized on g.s. peak.
Two theoretical curves (blue and red), two different model for the elementary K- production on proton.
Same hypernuclear wave-function (by Miloslav Sotona).
Red line: Bennhold-Mart (K MAID)
Blue line: Sagay Saclay-Lyon (SLA).
Curves are normalized on g.s. peak.
Theory = 5.4 nb/(GeV sr2 ) …!!!
Stat ~ 4.3 %Syst ~ 20 %
g.s. CrossSection = 5.00 nb/(GeV sr2 )
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Analysis on 12B spectrum : COMPARISON with models
New comparison: inclusion of ”all” predicted levels bring to a stronger disagreement for levels with in p-shell
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
H. Hotchi et al., Phys. Rev. C 64 (2001) 044302 H. Hotchi et al., Phys. Rev. C 64 (2001) 044302
E94-107 Hall A Experiment Vs. KEK-E369
12C(e,e’K)12B12C(e,e’K)12B 12C(,K+)12C
12C(,K+)12C
Statistical significance of core excited states:
€
Signal
Bckgnd> 7
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
E94-107 Hall A Experiment Vs. FINUDA (at Dane)
12C(e,e’K)12B12C(e,e’K)12B 12C(K-, )12C
12C(K-, )12C
Statistical significance of core excited states:
€
Signal
Bckgnd> 7
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
E94-107 Hall A Experiment Vs. HallC E89-009
12C(e,e’K)12B12C(e,e’K)12B 12C(e,e’K)12B
12C(e,e’K)12B
Miyoshi et al., PRL 90 (2003) 232502.
New analysis
Statistical significance of core excited states:
€
Signal
Bckgnd> 7
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
E94-107 Hall A Experiment: status of 12B data
12C(e,e’K)12B12C(e,e’K)12B
Statistical significance of core excited states:
€
Signal
Bckgnd> 7
Energy resolution is ~ 900 keV with old optics database
More than one year spent to improve the resolution
Although the new database does a very good job for single arm elastics data: 1.1 10-4 the expected resolution of less than 600 keV is not yet achieved
some more check and tuning has to be done, …but :
despite the fact that optimal resolution has not yet been obtained, the data are of extremely good quality
… to be published soon
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Results from last year run on 9Be target
Analysis of the reaction 9Be(e,e’K)9Li
(still preliminary)
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Missing energy (MeV)
Cou
nts
/ 4
00 k
eV
9Be(e,e’K)9Li9Be(e,e’K)9Li
Aerogel Kaon selection
RICH Kaon selection
JLAB Hall A E-94107: Preliminary Results on 9Be target
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Missing energy (MeV)
Cou
nts
/ 2
00 k
eV
Red line: Bennhold-Mart (K MAID)
Blue line: Sagay Saclay-Lyon (SLA)
Curves are normalized on g.s. peak.
Red line: Bennhold-Mart (K MAID)
Blue line: Sagay Saclay-Lyon (SLA)
Curves are normalized on g.s. peak.
JLAB Hall A E-94107: Preliminary Results on 9Be target
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
First Results from current experiment on WATERFALL target
Analysis of the reaction 16O(e,e’K)16N
and 1H(e,e’K)(elementary reaction)
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
2005 E-94107: Running on waterfall target
Be windows H2O “foil”
H2O “foil”
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
2005 E-94107: Preliminary spectra of missing energy
1H (e,e’K)1H (e,e’K)
16O(e,e’K)16N16O(e,e’K)16N
16O(e,e’K)16N
16O(e,e’K)16N
Low counting levels above Ethr.
16O(e,e’K)16N
16O(e,e’K)16N
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Analysis on 16N spectrum : FIT to the data
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
15N energy spectrum16N energy spectrum
Analysis on 16N spectrum : COMPARISON with models
High energy excited MULTIPLETS seems NOT WELL reproduced by the model.
-interaction here is in p-state, poorly known….
High energy excited MULTIPLETS seems NOT WELL reproduced by the model.
-interaction here is in p-state, poorly known….
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Analysis on 16N spectrum : COMPARISON with models
…SHIFTING “by hand” the positions of these MULTIPLETS in the model, while mantaining the predicted strength, a VERY GOOD agreement with the data can be reached.
…SHIFTING “by hand” the positions of these MULTIPLETS in the model, while mantaining the predicted strength, a VERY GOOD agreement with the data can be reached.
Work is in progress for a deeper physics interpretation.
Work is in progress for a deeper physics interpretation.
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
16O(e,e’K)16N16O(e,e’K)16N
E94-107 Hall A Experiment Vs. KEK-E336
16O(,K+)16O16O(,K+)16O
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
16O(e,e’K)16N16O(e,e’K)16N
E94-107 Hall A Experiment Vs. -ray spectroscopy at BNL
16O(K-, ) 16O16O(K-, ) 16O
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Importance of the elementary reaction 1H(e,e’K)at low Q2
In K+ photoproduction on proton there is a clear inconsistency of the experimental data (CLAS vs SAPHIR) at K
cm < 40 deg. Electroproduction at very low Q2 can clarify this inconsistency, which is also important for calculation for hypernuclear cross sections.
1H (e,e’K)1H (e,e’K)K+ photoproduction
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
Conclusions:
Experiment E94-107 at Jefferson Lab: GOAL is to carry out a systematic
study of light hypernuclei (shell-p).
The experiment required important modifications on the Hall A apparatus.
Good quality data on 12C and 9Be targets (12Band 9Li hypernuclei) have
been taken last year
New experimental equipments showed excellent performance.
The RICH detector performed as expected and it is crucial in the kaon
selection.
On-going Analysis of data on 12Ctargetis showing new information on
12Band interesting comparison with theory for 12B and 9Li.
VERY Promising physics is coming out from new data on the waterfall target
for 16Nhypernuclear spectroscopy - also for p(e,e’K)X-Sect. measurement
Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec 6 2005
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