High Resolution Hypernuclear Spectroscopy

1
High Resolution Hypernuclear Spectroscopy
experiment e94-107 Update

• 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
2
High Resolution Hypernuclear Spectroscopy
experiment e94-107 Update
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
3
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 (L-N interaction).
• Extension of physics on N-N interaction to
  system with S?0
• Internal nuclear shell are not
• Pauli-blocked for hyperons.

Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
4
HYPERNUCLEI and ASTROPHYSICS

• Strange baryons may appear in neutral b-stable
  matter through process like

• 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
5
Hypernuclei - historical background -
experimental techniques
1953 discovery of first hypernucleus by
Danysz and Pniewski while studying cosmic
radiation with emulsion techniques
To commemorate their discovery the above postcard
was issued by the Polish Post in May 1993
1962 The first double LL Hypernucleus
was discovered in a nuclear emulsion irradiated
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
6
Hypernuclei - historical background -
experimental techniques
1953 ? 1970 hypernuclear identification with
visualizing techniques emulsions, bubble
chambers
Elementary reaction on neutron
1970 ? Now Spectrometers at accelerators CER
N (up to 1980) BNL (K-, p-) and (K, p)
production methods KEK (K-, p-) and (K, p)
production methods
e.g.
gt 2000 Stopped kaons at DAFNE (FINUDA)
(K-stop, p-)
Elementary reaction on proton
gt 2000 The new electromagnetic way
HYPERNUCLEAR production with ELECTRON BEAM at
JLAB
e.g.
7
Present status of L Hypernuclear Spectroscopy
O. Hashimoto and H. Tamura, Prog. Part. Nucl.
Phys, in press.
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
8
What do we learn from hypernuclear spectroscopy
Hypernuclei and the L-N interaction
weak coupling model
(parent nucleus) (L hyperon)
(doublet state)
D
SL
SN
T
V
Each of the 5 radial integral (V, D, SL , SN, T)
can be phenomenologically determined from the
low lying level structure of p-shell hypernuclei
Low-lying levels of L Hypernuclei
Hypernuclear Fine Structure
SN
Split by LN spin dependent interaction
(A-1)
D
AL
, SL
, T
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
9
E94-107 Experiment High Resolution 1p Shell
Hypernuclear Spectroscopy (spokespersons F.
Garibaldi, S. Frullani, J. Le Rose, P. Markowitz,
T. Saito Hall A Coll.)
Electroproduction of hypernuclei by the
reaction

• Spin flip states
• p?L Production of mirror nuclei / n rich
  hypernuclei
• High energy resolution

• Nuclear targets and resulting hypernuclei
• 9Be ? 9LiL (spin doublets, information on
  s-s term of L-N interaction potential)
• 12C ? 12BL (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 ? 16NL (details of the hyper. spectrum
  also depends on L single particle spin-orbit
  splitting )

Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
10
Experimental requirements

• 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, 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 HRSSepta with accurate optics
  calibrations

1. DE/E 2.5 x 10-5 2. DP/P (HRS septum)
10-4 3. Straggling, energy loss
600 keV
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
11
Data taking, Kinematics, Counting rates

• 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

• Ebeam 4.016 3.777 3.656 GeV
• Pe 1.80 1.56 1.44 GeV/c
• Pk 1.96 GeV/c
• qe qK 6
• Eg ? 2.2 GeV Q2 0.079 (GeV/c)2
• Beam current 100 mA 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
12
SEPTUM magnets in Hall A new optics DB for the
DQQDQ system
NEW DB 2005
OLD DB 2004
FWHM 1.1x10-4
FWHM 2.2x10-4
Thanks to Doug and co-workers
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
13
KAON Id Requirements physics case
Signal Vs. Background
Process Rates
signal Bound states (e,eK) 10-4 10-2
accidentals (e,e)(e,p) (e,e)(e,p) (e,e)(e,k) 100 100 0.1
Monte Carlo

• Forward angles ? higher background of p and p
• TOF and 2 Threshold Cherenkov NOT sufficient
  for unambiguous kaon identification
• RICH DETECTOR

Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
14
RICH detector C6F14/CsI proximity focusing RICH
MIP
Cherenkov angle resolution
Separation Power
Performances Np.e. of detected photons
(p.e.) and sq (angular resolution)
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
15
Rich Performance key parameters
Npe for p and p
Cherenkov angle for p
Nclusters
Npe p/p ratio
Cherenkov average angle (rad)
Angular resolution
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
16
Rich PID Effect of Kaon selection
Coincidence Time selecting kaons on Aerogels and
on RICH
AERO K
AERO K RICH K
2004
p
P
K
Pion rejection factor 1000
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
17
Rich PID Effect of Kaon selection
Coincidence Time selecting kaons on Aerogels and
on RICH
AERO K
AERO K RICH K
2005
K
P
GREATLY improved AEROGEL performance!
p
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
18
Shell model excitation levels for 12BL
dependence on the LN potential - different set
of potential params.
12BL energy spectrum
11C energy spectrum
J2, 3
J2, 3
J2, 3
x 0pL
J2-
J2-
J2-
x 0sL
J3/2- E5 MeV
J5/2- E4.5 MeV
J1-
J1-
x 0sL
J1/2- E2 MeV
J1-
J1-, 2- doublet
x 0sL
J3/2- E0.0 MeV
YNG potential
Canonical Standard
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
19
Monte Carlo simulation of 12BL excitation-energy
levels produced on 12C target
Monte Carlo
12C(e,eK)12BL
d
a
c
b
Absolute and relative positions of resolved
levels a,b,c,d, may provide information on
parameters of L-N interaction potential and its
terms (spin-spin, spin-orbit, tensor, )
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
20
Monte Carlo simulation of 9LiL excitation-energy
levels Produced on 9Be target
Excitation-energy levels of 9LiL hypernucleus,
especially from the first-doublet levels a and b,
would provide important information on D, SL and
T terms of the L-N interaction. Separation of c
and d doublets may provide information on the
spin-orbit term SN
Monte Carlo
9Be(e,eK)9LiL
c
d
a
b
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
21
Theoretical model for 16NL excitation-energy on
16O target

• The structure of underlying nucleus 15N is
  dominated by
• J1/2-proton-hole state in 0p1/2 shell - ground
  state
• J3/2- 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 L-N residual
interaction but also on the L single particle
spin-orbit splitting (difference in energy of
0p3/2 and 0p1/2 L states)
16O(e,eK)16NL
22
Results from last year run on 12C target
Analysis of the reaction 12C(e,eK)12BL
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
23
Results on 12C target Hypernuclear Spectrum of
12BL
Missing energy (MeV)
12C(e,eK)12BL
g.s.
lt 1 MeV FWHM
As obtained with the old optics DB. The new one
does not improve the resolution still under
analysis/investigation
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
24
Analysis on 12BL spectrum Aerogel vs. RICH
K-selection
12C(e,eK)12BL
Aerogel Kaon selection
RICH Kaon selection
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
25
Analysis on 12BL spectrum FIT to the data
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
26
JLAB Hall A E94-107 preliminary comparison with
theory for 12BL hypernucleus
12C(e,eK)12BL
Two theoretical curves (blue and red), two
different model for the elementary K-L
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.
Counts / 200 keV
Missing energy (MeV)
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
27
JLAB Hall A E94-107 preliminary comparison with
theory for 12BL hypernucleus
12C(e,eK)12BL
Two theoretical curves (blue and red), two
different model for the elementary K-L
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.
Counts / 200 keV
Missing energy (MeV)
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
28
Analysis on 12BL spectrum COMPARISON with models
New comparison inclusion of all predicted
levels bring to a stronger disagreement for
levels with L in p-shell
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
29
E94-107 Hall A Experiment Vs. KEK-E369
12C(e,eK)12BL
12C(p,K)12CL
Statistical significance of core excited states
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
30
E94-107 Hall A Experiment Vs. FINUDA (at DaFne)
12C(e,eK)12BL
12C(K- , p-)12CL
Statistical significance of core excited states
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
31
E94-107 Hall A Experiment Vs. HallC E89-009
12C(e,eK)12BL
12C(e,eK)12BL
Miyoshi et al., PRL 90 (2003) 232502.
Statistical significance of core excited states
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
32
E94-107 Hall A Experiment status of 12BL data
12C(e,eK)12BL

• 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

Statistical significance of core excited states
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
33
Results from last year run on 9Be target
Analysis of the reaction 9Be(e,eK)9LiL
(still preliminary)
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
34
JLAB Hall A E-94107 Preliminary Results on 9Be
target
9Be(e,eK)9LiL
Counts / 400 keV
Aerogel Kaon selection
RICH Kaon selection
Missing energy (MeV)
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
35
JLAB Hall A E-94107 Preliminary Results on 9Be
target
Red line Bennhold-Mart (K MAID) Blue line Sagay
Saclay-Lyon (SLA) Curves are normalized on g.s.
peak.
Counts / 200 keV
Missing energy (MeV)
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
36
First Results from current experiment on
WATERFALL target
Analysis of the reaction 16O(e,eK)16NL
and 1H(e,eK)L (elementary reaction)
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
37
2005 E-94107 Running on waterfall target
H2O foil
Be windows
H2O foil
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
38
2005 E-94107 Preliminary spectra of missing
energy
1H (e,eK)L
16O(e,eK)16NL
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
39
Analysis on 16NL spectrum FIT to the data
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
40
Analysis on 16NL spectrum COMPARISON with models
High energy excited MULTIPLETS seems NOT WELL
reproduced by the model. L-interaction here is
in p-state, poorly known.
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
41
Analysis on 16NL 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.
Work is in progress for a deeper physics
interpretation.
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
42
E94-107 Hall A Experiment Vs. KEK-E336
16O(e,eK)16NL
16O(p,K)16OL
Very Preliminary
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
43
E94-107 Hall A Experiment Vs. g-ray spectroscopy
at BNL
16O(e,eK)16NL
16O(K-, p- g) 16OL
Very Preliminary
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
44
Importance of the elementary reaction 1H(e,eK)L
at low Q2
KL photoproduction
1H (e,eK)L
In KL photoproduction on proton there is a clear
inconsistency of the experimental data (CLAS vs
SAPHIR) at QKcm lt 40 deg. Electroproduction at
very low Q2 can clarify this inconsistency, which
is also important for calculation for
hypernuclear cross sections.
Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005
45
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 (12BL
  and 9LiL 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 12C target is
  showing new information on 12BL and interesting
  comparison with theory for 12BL and 9LiL.
• VERY Promising physics is coming out from new
  data on the waterfall target for 16NL
  hypernuclear spectroscopy - also for p(e,eK)L
  X-Sect. measurement

Mauro Iodice e94107 update - Hall A
Collaboration Meeting, JLAB, Dec 6 2005