high resolution hypernuclear spectroscopy in hall a
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Hypernuclei, – N interaction
Electroproduction of hypernuclei
E94-107 experiment UPDATE
Experimental equipment and setup
Kaon identification RICH detector
Analysis results of 2004 run
Preliminary results of 2005 run
E07-012 proposed experiment
Conclusions
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
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
JLAB Hall A E94107
COLLABORATION
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
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.
Experimental goals :
Spectroscopy – Excitation Energy – doublet splitting
Information on -N interaction
Hypernuclei
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
E94107 experiment has taken data in two separate period on 2004. Data have been collected on solid targets. The second part of the experiment is currently running in Hall A using the waterfall target
January 2004 12C target and commissioning of waterfall target
April 2004 12C target and May 2004 9Be
June 2005 Waterfall target for hypernuclear state production on 16O
Approved Experiment E07012 to study the angular dependence of
strangeness electroproduction
Data Taking and Future Plan
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
“weak coupling model”
(parent nucleus) ( hyperon) (doublet state)21
11 )( AHypA JJshellsJ
N interaction potential:VN = Vo(r) V central
+ V(r) N · (spin-spin)
+ Vso(r) N· (spin-orbit)
+ Vso(r) N· NN(spin-orbit)
+ VT(r) S12 T tensor
9Be
9Li9B
e
9Li excita
tion e
nerg
yHypernuclei and -N interaction
9Be 9Li
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
Electroproduction of Hypernuclei
e
p
K+
e’
*
N … N
nucleus
Hypernucleus
p
beam
Scattered electronDetected by HRSe
Kaon detected by HRSk
N … N
1 ZKeZe AA 1 ZKeZe AA
High luminosity, high duty cycle, excellent beam energy spread
Better energy resolution than hadronic induced reactions, BUT smaller cross section
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
Electroproduction of hypernuclei by the reaction:
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) 16O 16N(details of the hypernuclear spectrum also depends on single particle
spin-orbit splitting)
Experimental requirements:1. Excellent Energy Resolution (Best performance for Beam and HRS)2. Detection at very forward angles (6° to obtain reasonably high counting
rates septum magnets)
3. Excellent Particle Identification system (PID) for unambiguous kaon selection RICH
E94-107 Experiment:“High Resolution 1p Shell Hypernuclear Spectroscopy”(spokespersons: F. Garibaldi, S. Frullani, J. Le Rose, P. Markowitz, T. Saito – Hall A Coll.)
1 ZKeZe AA 1 ZKeZe AA
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
SEPTUM magnets in Hall A
FWHM = 1.1x10-4
=20x20 mrad2
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
Carbon Peaks
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
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
Hadron identification using Aerogel Threshold Cherenkov detectors
p
k All events
AERO1 n=1.015
AERO2 n=1.055
p
k
ph = 1.7 : 2.5 GeV/c
Protons = A1•A2
Pions = A1•A2
Kaons = A1•A2
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
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
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
RICH detector –C6F14/CsI proximity focusing RICH
Ch“MIP”
Performances: Np.e. # of detected photons (p.e.)and (angular resolution)
..
..
ep
ep
Nc
Cherenkov angle resolution
Separation Power
c n12
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
The RICH detector at Jefferson Lab
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
Rich – PID – Effect of ‘Kaon selection’:
P
K
Coincidence Time selecting kaons on Aerogels and on RICH:
AERO K AERO K && RICH K
RICH Pion rejection factor ~ 1000
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
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!
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
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
NN
T
NNNSO
NSO
N
rrS
TSrV
SrV
SrV
rV
rVV
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, …)
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
Results from 12C target
Analysis of the reaction 12C(e,e’K)12B
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
Aerogel Kaon selection
RICH Kaon selection
12C(e,e’K)12B12C(e,e’K)12B
Signal
Bckgnd2.5
Signal
Bckgnd 7
Spectroscopy analysis of 12B : Aerogel vs. RICH K-selection
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
12C(e,e’K)12B12C(e,e’K)12B
635 keV FWHM
Missing energy (MeV)
Results on 12C target – Hypernuclear Spectrum of 12B
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
Experiment
SLA Model
M. Iodice et al, submitted to Phys Rev Lett, arXiv:0705:3332
Theoretical model for 16Nexcitation-energy on 16O target
The structure of underlying nucleus15N 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
Preliminary Results on WATERFALL target
Analysis of the reaction 16O(e,e’K)16N
and 1H(e,e’K)(elementary reaction)
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
2005 E-94107: Running on waterfall target
Be windows H2O “foil”
H2O “foil”
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
2005 E-94107: Preliminary Analysis
1H (e,e’K)1H (e,e’K)
16O(e,e’K)16N16O(e,e’K)16N
Low counting levels above Ethr.
16O(e,e’K)16N
16O(e,e’K)16N
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
Missing Energy (MeV)
g.s. missing energy: -1.44 0.09 MeV Theor –1.56 MeV
9Be(e,e’K)9Li
a c db
)())((3
(Tensor))(
orbitspin)(
orbitspin)(
spin)(spin)(
(central)V)(
12
12
0N
NN
T
NNNSO
NSO
N
rrS
TSrV
SlrV
SlrV
rV
rVV
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
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
Results on 9Be target
Analysis of the reaction 9Be(e,e’K)9Li
(still preliminary)
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
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
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
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
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
The Angular Dependence of 16O(e, e K) 16N and H(e,e K+)
- hypernuclear physics
- the electromagnetic approach
- recent results
- motivation
- the elementary reaction
- angular distribution
- the apparatus
- kinematics and counting rates
- beam time request
- summary and conclusion
proposal for PAC 31 (F. Garibaldi January 0507 - Hall A Collaboration meeting - Jlab)
Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
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 performs as expected and it is crucial in the kaon selection.
Submitted paper on 12Ctarget analysisis showing new information on 12B-
interesting comparison with theory for 12B and 9Li.
VERY Promising physics is coming out from preliminary analysis on
16Nhypernuclear spectroscopy
Approved Experiment on angular dependence of strangeness
electroproductionFrancesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007
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