Transcript Study of light hypernuclei by the (e,e’K+) reaction

Study of light hypernuclei
by the (e,e’K+) reaction
Graduate school of science, Tohoku Univ.
Toshiyuki Gogami
JLab E05-115 collaboration, 2009, JLab Hall-C
1
Contents
• (e,e’K+) spectroscopic experiment in JLab
– 7ΛHe,9ΛLi,10ΛBe, 16ΛN, 12ΛB, 28ΛAl,52ΛV
• Precision light Λ hypernuclear spectroscopy
– 7ΛHe (preliminary result)
ΛN charge symmetry breaking
APFB2011 in Korea (T.Gogami)
2
Λ hypernuclear spectroscopy
52
LV
Updated from: O. Hashimoto and H. Tamura, Prog. Part. Nucl. Phys. 57 (2006) 564.3
Spectroscopic experiment
by (e,e’K+) reaction
e
p
e’-Spectrometer
e-
e
u
u
d
pe’
e + p ➝ e’ + K+ + Λ
Feynman diagram
γ* u K+
–s
s
u Λ
d
γ*
p
n
Λ
target nucleus
1.
2.
3.
Missing Mass HHY
K+
K+-Spectrometer
pK+
Large Momentum transfer
• Λ can be bounded in deeper orbit
Λ’s spin at forward angle
• Spin flip ~ spin non-flip
Proton  Λ
• Absolute mass value calibration
APFB2011 in Korea (T.Gogami)
4
JLab E05-115 experimental setup
e + p → e’ + Λ + K+
2×10-4
7 [msr]
3 – 12 [deg]
7Li
2×10-4
8.5 [msr]
2 – 12 [deg]
, 9Be , 10B , 12C , 52Cr
• (e,e’K+) experiment
Primary beam
• High intensity
Thin target (~100 [mg/cm2])
• High quality
APFB2011 in Korea (T.Gogami)
1.
2.
3.
Coincidence experiment
(K+ and e-)
Small cross section
( ~100 [nb/sr] ) 1/1000
Energy resolution
5
Sub MeV (FWHM)
JLab CEBAF ( Continuance Electron
Beam Accelerator Facility )
• (e,e’K+) experiment
1.
2.
3.
Coincidence experiment
(K+ and e-)
Small cross section
( ~100 [nb/sr] ) 1/1000
Energy resolution
sub MeV (FWHM)
• Requirements for accelerator
1. High duty factor (~100%)
2. High intensity ( >a few 10 μA )
3. Small emittance ( ~2 [mm・μrad] )
Small ΔE/E ( <1×10-4 )
100 [m]
CEBAF was unique
facility
before MAMI updated
Experimental Hall
APFB2011 in Korea (T.Gogami)
6
(e,e’K+) experiment in JLab
2000
Proof of feasibility
1st generation exp. JLab E89-009
e’-spectrometer + K+-spectrometer
12 B
Λ
~ 750 [keV] (FWHM)
Hall-C
2005
Establish exp. method
2004
JLab E94-107
(K+, e+)-spectrometers + septum
9 Li,12 B,16 N
Λ
Λ
Λ
~ 670 [keV] (FWHM)
Hall-A
2nd generation exp. JLab E01-011
e’-spec. Optimized configuration + HKS(K+)
7 He,12 B,28 Al
Λ
Λ
Λ
Hall-C
~ 600 [keV] (FWHM)
2009
Up
to
Medium
heavy
rd
3 generation exp. JLab E05-115
HES(e’) Optimized configuration + HKS(K+)
7 He,9 Li,10 Be, 12 B,52 V
Λ
Λ
Λ
Λ
Λ
Hall-C
≤ 500 [keV] (FWHM)
APFB2011 in Korea (T.Gogami)
Avoid huge background at
very forward angle
7
Analysis status of E05-115
~40 hours
(5 shifts)
JLab E05-115
p(e,e’K+)Λ,Σ0
• p(e,e’K+)Λ,Σ0
 HES-HKS basic system works well
Very preliminary
• Analysis is in progress
1. Energy (mass) calibration
2. Developing new code for high multiplicity
data
Λ and Σ0 can be seen
at the same time
2009
Up
to
Medium
heavy
rd
3 generation exp. JLab E05-115
HES(e’) Optimized configuration + HKS(K+)
7 He,9 Li,10 Be, 12 B,52 V
Λ
Λ
Λ
Λ
Λ
Hall-C
≤ 500 [keV] (FWHM)
APFB2011 in Korea (T.Gogami)
E.M background ∝ ~Z2
8
Experimental data of A=7 system
Four-body cluster model for T=1 iso-triplet hypernuclei
(E.Hiyama et al., NPC 80, 2009)
Old 7ΛHe data
( M.Juric, NPB 52, 1973 )
α+Λ+N+N
-6.650.03 0.2 MeV JLab E01-011
7
+ 7
from α L n n Li(e,e’K ) ΛHe
Preliminary
-BL [MeV]
Compare to theoretical calculation
9
APFB2011 in Korea (T.Gogami)
Theoretical calculation of A=7 system
Four-body cluster model for T=1 iso-triplet hypernuclei
(E.Hiyama et al., NPC 80, 2009)
Old 7ΛHe data
( M.Juric, NPB 52, 1973 )
α+Λ+N+N
-6.650.03 0.2 MeV JLab E01-011
7
+ 7
from α L n n Li(e,e’K ) ΛHe
Preliminary
-BL [MeV]
Compare to theoretical calculation
10
APFB2011 in Korea (T.Gogami)
Theoretical calculation of A=7 system
Four-body cluster model for T=1 iso-triplet hypernuclei
JLab E01-011
7Li(e,e’K+)7 He
(E.Hiyama et al., PRC 80, 2009)
Λ
-6.650.03 0.2 MeV
α+Λ+N+N
from α L n n
Preliminary
-BL (MeV)
-5.41
CSB interaction is determined to
reproduce BΛ of 4ΛH and 4ΛHe.
Decay pion spectroscopy
Will be talked by E.Hiyama in
APFB2011 in Korea (T.Gogami)
11
Plenary 6 session(8/24)
Summary
• (e,e’K+) spectroscopic exp. in JLab
– E89-009 (2000,Hall-C) 12ΛB
– E94-107 (2004,Hall-A) 9ΛLi,12ΛB,16ΛN
– E01-011 (2005,Hall-C) 7ΛHe,12ΛB,28ΛAl Final analysis stage
– E05-115 (2009,Hall-C) 7ΛHe,9ΛLi,10ΛBe, 12ΛB,52ΛV
Analysis stage
• Precision light Λ hypernuclear spectroscopy
– 7ΛHe (preliminary result by E01-011)
– 10ΛBe (analyzing)
ΛN charge symmetry breaking
APFB2011 in Korea (T.Gogami)
12
End
Thank you very much
APFB2011 in Korea (T.Gogami)
13