Transcript Spectroscopic Investigation of P-shell Λ hypernuclei by the (e,e'K+) Reaction -Analysis Update of the Jlab Experiment E05115Chunhua Chen Hampton Universithy.

Spectroscopic Investigation
of P-shell Λ
hypernuclei by the (e,e'K+) Reaction
-Analysis Update
of the Jlab
Experiment E05115Chunhua Chen
Hampton Universithy
Outline

Experimental Goal of E05115

Kinematics of the E05115

Experimental Setup of E05115

System calibration procedure and status

Preliminary results

Summary and to do
Experimental Goal
The 3rd Generation Hypernuclear Spectroscopy in JLab-HallC
Spectroscopy of Medium - heavy hypernucleus

52Cr(e,e’K+) 52
LV
L single particle nature in the mean field

quark picture vs. conventional picture

Spectroscopy of Light L hypernuclei



LN interactions, ls splitting, Charge Symmetry Breaking
p shell hypernuclei : 12C(e,e'K+)12ΛB , 7Li(e,e'K+)7ΛHe,
10B(e,e'K+)10
ΛBe
and 9Be(e'K+)9ΛLi
Calibration by the elementary process p(e,e’K+)Λ or Σ: H2O and CH2
,
Kinematics of the E05-115 Experiment
Electron beam
Momentum: 0.844GeV/c ±17%
Angular acceptance: 3°〜9°
L
Momentum: 2.344GeV/c
+p →L+K+
Scattered electron
Target
nucleus
Coincidence
measurement
1.5GeV γ*
p
K+
Momentum: 1.2GeV/c ±12.5%
Angular acceptance : 1°〜13°
Experimental Setup
HES
Splitter Magnet
HKS
PreChicane-SPL-(HKS+HES) Configuration
Experimental Setup
-Detector PackageHES Detectors
EDC2
EDC1
e’
HES-D
EHOD2
EHOD1
Calibration Procedure of the Spectrometer System
Magnetic field study
Forward
Tuning
A&B&C
Field map
Geant4 Simulation
Focal plane pattern
matrices
Real Data
Initial
state
Backward
tuning
Matching level
Focal plane pattern
Matching
level
SS pattern
Nonlinear Least
Chi2 fitting
Kinematical scan
A
B
SS hole
Independent
C
level
Λ & Σ mass
Kinematical
spectroscopy
parameters
mass spectroscopy
Forward Optics Tuning
Beam
Kaon
Q2
Q1
Target
Purple:
simulation
green:
Real HES
SS data
Purple:Geant4
Real HKS
SS data Blue:
Geant4
Simulation
Splitter field contour on xoz plane
The leakage of splitter fringe field causes the cross
talk between the splitter and quadrupoles
Forward Optics Tuning
The asymmetry functions are introduced and tuned for
HKS&HES quadruple field Bx and By, independently.
The Mass Status of Forward Optics Tuning
Start Point
after forward tuning
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𝑀𝑀 = 𝑓(Ebeam , Pk , xt’k, yt’k , Pe, , xt’e, ,yt’e’ )
= 𝑓(Ebeam0 + 𝛥Ebeam0 , Pk0 +𝛥Pk0, xt’k , yt’k ,
Pe′0+𝛥Pe′0, xt’e, yt’e′)
𝑥𝑡 ′
𝑦𝑡 ′
δ
= 𝑀
𝑀_𝑎𝑛𝑔𝑙𝑒
𝑀_𝑚𝑜𝑚𝑒𝑛𝑡𝑢𝑚
=
𝑃 = 𝑃0(1+δ/100)
ΔEbeam0
optimization
Kinematical
Calibration
ΔPK,ΔPe
optimization
𝑥𝑓
𝑥𝑓′
𝑦𝑓
𝑦𝑓′
𝑥𝑓
𝑥𝑓′
𝑦𝑓
𝑦𝑓′
Beam Energy
Scan
𝑓𝑖𝑡
𝜒12 = 𝜔Λ 𝑚Λ − 𝑚Λ0
𝑓𝑖𝑡 2
𝜒22 = 𝜔Λ 𝜎Λ
2
𝜎Λ 2 + 𝜔 𝑚 𝑓𝑖𝑡 − 𝑚0
Σ
Σ
Σ
𝑓𝑖𝑡 2
< 𝜎Λ >2 + 𝜔Σ 𝜎Σ
2
𝜎Σ 2
𝑓𝑖𝑡 2
< 𝜎Σ >2 + 𝜔𝑔𝑠 𝜎𝑔𝑠
iterate
Optical
Calibration
Momentum
Matrix
iterate
Angle
Matrix
Nonlinear
least 𝝌2 fitting
gs : 12ΛBgs
< 𝜎𝑔𝑠 >2
Start Point
σ~2.7MeV
FWHM~2.6MeV
Fitting Function:Cauchy+pol3
Particle
Mean(MeV)
FWHM
Λ
0.4495
2.832
Σ0
76.74
3.27
H2O target
Beam Momentum: 2.344GeV/c + 20 MeV/c
Preliminary Status
FWHM
~1.675MeV
#1
#2
FWHM
~1.775MeV
FWHM
~1.565MeV
Peak#
Mean(MeV)
σ (MeV)
1
-11.39
0.367
2
-0.40
~1.8
FWHM
~2.0MeV
Preliminary Result
7
ΛHe
E01011 data
3/2+&5/2+
6He
core
n

n
E. Hiyama, et al., PRC53 2078 (1996)
Preliminary Result
10
ΛBe –
7.94
5/2-
6.76
6.38
9/2+7/2
5.59
4.70
3/23/2+
3.04
2.78
2.43
1.68
5/2+1/2
5/21/2+
0.00
3/2-
Low Lying 9Be
Level Structure
10 Be
Λ
2-1
(< 0.1)
10 Be
L
Missing mass status –
9 Li
L
Hall A Result
(To be published soon)
Summary and to do

By current calibration method, we are able to get clear
mass spectroscopy , which is not included in the calibration
data set;

Current resolution is still factor of 2 away from expected
resolution, the iteration will continue to improve the
optical matrices as well as the kinematics;

Other issue: High multiplicity tracking problem for heavy
target data.
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Back up
19
New Data Sets
#1
The improvement of the
resolution is small with the old
data, since the statistic of
12 Bgs is small, which is
Λ
momentum sensitive .
All carbon runs with clear
beam current and
nominal beam energy.
There are around 414
events in peak #1, and
the S/N is around 2.35.
Problem
Since the improvement of the resolution still
small, increase the weight of 12ΛBgs by factor
of 4 on the base of the statistical weight .
7 He
Λ
Missing Mass
σ ~ 1.0 MeV
Target Straggling
σ~3.2MeV
Tune Angle matrix
and momentum
matrix at same time
σ~2.7MeV
Preliminary Status
-7ΛHe-
#1
#2
Peak #
Mean(MeV)
σ (MeV)
1
-5.46
0.549
2
-3.94
4.66
E01011 data
Resolution : ~510 keV (FWHM) for g.s.
Data taking : ~30 hours w/ 30 mA
Theoretical calculation
Binding energy: Hiyama w/o CSB
1/2+ (-BΛ=-5.37)
First turn optics tune with CH2 Data
Particle
Mean(MeV)
FWHM
Λ
0.2098
2.122
Σ0
77.41
2.456
First turn optics tune with CH2 Data
FWHM~2.9MeV
H2O target
FWHM~2.6MeV
H2O target
Beam Momentum: 2.344GeV/c + 20 MeV/c
First turn optics tune with CH2 Data
FWHM~2.9MeV
H2O target
FWHM~2.6MeV
H2O target
Beam Momentum: 2.344GeV/c + 20 MeV/c
Data sets
Target
Mass
Events # above BG
S/N
CH2
Λ
9976
3.54
Σ0
2650
1.40
H2O(Pe~2.364)
Λ
283
2.96
C12 (BC=20uA)
12
Λ𝐵
309
1.61
e , e+ background in GEANT
simulation
HKS
KDC1
KDC2
e- , e+
Vacuum chamber
(sus304)
e+


NMR port
(sus304)



Generated particle : e+
Distribution : spherical uniform
Momentum : 860 – 1000 [MeV/c]
Angle : 0 – 2 [mrad]
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1000 events
Calibration procedure
-Beam Energy Scan-
𝑓𝑖𝑡
𝑓𝑖𝑡
𝜒12 = 𝜔Λ (𝑚Λ − 𝑚Λ0 ) 𝜎Λ 2 + 𝜔Σ (𝑚Σ − 𝑚Σ0 ) 𝜎Σ 2
𝑓𝑖𝑡
𝑓𝑖𝑡
𝑓𝑖𝑡
𝜒22 = 𝜔Λ (𝜎Λ ) < 𝜎Λ >2 + 𝜔Σ (𝜎Σ ) < 𝜎Σ >2 + 𝜔𝑔𝑠 (𝜎𝑔𝑠 ) < 𝜎𝑔𝑠 >2
ωi:statistic weigth
Coincident Trigger Set
HKS :
HES:
HKStrigger=(CP)×(K)
CP=(KTOF1X)×(KTOF1Y)×(KTOF2X)
HEStrigger=(EHODO1)×(EHODO2)
×:AND
K=WC×𝐴𝐶
Real
events
 Coincident Time:
Accidental
PID cut is applied and path length has been done
The correlation of HKS
target time and HES target
time, give us the
coincident spectrum:
K+
tar
Tcoin  T  T
e'
tar
Kinematics of the
E05-115 Experiment
Electron beam
Momentum: 0.844GeV/c ±17%
Angular acceptance: 3°〜9°
L
Momentum: 2.344GeV/c
+p →L+K+
Scattered electron
Target
nucleus
Coincidence
measurement
1.5GeV γ*
p
K+
M.Q.Tran et al.
PLB445 (1998) 20
Momentum: 1.2GeV/c ±12.5%
Angular acceptance : 1°〜13°
Preliminary Status
#1
#1
FWHM
FWHM
~1.675Me
V ~1.675Me
V
#2
#2
FWHM
~1.775MeV
FWHM
~1.565MeV
~1.565Me
V
Peak#
Mean(MeV)
σ (MeV)
1
-11.39
0.367
2
-0.40
~1.8
FWHM
~2.0MeV
Spectrometer System Calibration
-Minimize 𝜒2 Kinematics calibration: utilizing well known masses of L,  produced
from CH2 , 12ΛBgs from
precision ~100keV
12C
to determine binding energy to a level of
𝑓𝑖𝑡
𝑓𝑖𝑡
𝜒12 = 𝜔Λ (𝑚Λ − 𝑚Λ0 ) 𝜎Λ 2 + 𝜔Σ (𝑚Σ − 𝑚Σ0 ) 𝜎Σ 2
𝑓𝑖𝑡
𝑓𝑖𝑡
𝑓𝑖𝑡
𝜒22 = 𝜔Λ (𝜎Λ ) < 𝜎Λ >2 + 𝜔Σ (𝜎Σ ) < 𝜎Σ >2 + 𝜔𝑔𝑠 (𝜎𝑔𝑠 ) < 𝜎𝑔𝑠 >2
 Optical calibration: Minimize Chisquare w.r.t
reconstruction matrix M by an Nonlinear Least Square
method.
Mgs: fitted mean
MΛ &MΣ : theoretical data
ωi : statistic weigth
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PreChicane-SPL-(HKS+HES) Configuration
Calibration Data Set
Target
Mass
CH2
Λ
Σ
12C
H2O
12B
Λ
Λ
Beam P(MeV/c)
~2.344
~2.344
2.364
Beam Current(uA)
~2
~20
~3.5
Mass
spectroscopy of
Λ,Σ and 12ΛB
(mean and peak
width)
38