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Recent Spectroscopic Investigation of P-Shell Λ-hypernuclei bythe (e, e’K+) Reaction-Analysis Status of E05115-
Chunhua Chen (陈春花)Hampton University
July 18,2012
The fourth workshop on hadron physics in China and Opportunities in USA
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Introduction
Merits of (e,e’K+) experiment: Large momentum transfer → Excitation of deeply-bound state p to conversion → Mirror or Neutron-rich hypernuclei Production of both spin-flip/non-flip states; High resolution because of the quality of the CEBAF beam
Merits of (e,e’K+) experiment: Large momentum transfer → Excitation of deeply-bound state p to conversion → Mirror or Neutron-rich hypernuclei Production of both spin-flip/non-flip states; High resolution because of the quality of the CEBAF beam
Experimental Goals: Spectroscopy of Medium - heavy hypernucleus
52Cr(e,e’K+) 52LV
Spectroscopy of Light L hypernuclei- p shell hypernuclei
12C(e,e'K+)12ΛB , 7Li(e,e'K+)7
ΛHe, 10B(e,e'K+)10ΛBe , and 9Be(e'K+)9
ΛLi
Calibration by the elementary process p(e,e’K+)or : H2O and CH2
Results are important in determining , SN and V0 terms from s states and S term from states with at higher orbits Dr. Tang’s Talk
E05115 : The 3rd generation spectroscopic investigation of Lambda hypernuclei by the
Reaction (e,e’K+) at Jlab Hall C
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Experimental Setup
Splitter Magnet
HKS
HES
Bremsstralung flux
Virtual photon flux factor
K+
e’
e
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PreChicane-SPL-(HKS+HES) Configuration
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Kinematics of the E05-115 Experiment
+p →+K+
Momentum: 2.344GeV/c
Momentum: 0.844GeV/c ±17%Angular acceptance: 3° 〜 9°
Momentum: 1.2GeV/c ±12.5%
Angular acceptance : 1° 〜 13°
1.5GeV γ*
Scattered electron
K+
Electron beam
Target nucleus
pCoincidence
measurement
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Experimental Setup -Detector Package-
HES-D
e’
EHOD2
EHOD1
EDC2EDC1
HES Detectors
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Analysis Flow Chart
Tracking(KDC)
TOF(Hodoscopes)
KID(AC,WC,LC)
HKS Focal Plane (X,X’,Y,Y’,Tfp)
HK
S Optics(HKS+Splitter)
HKS Target Plane (X’, Y’, P, Ttar)
Tracking(EDC)
TOF(Hodoscopes)
HES Focal Plane (X,X’,Y,Y’, Tfp)
HES Optics
(HES+Splitter) HES Target Plane (X’, Y’, P, Ttar)
Coincident(RF )
Kinematics Correction(Beam, Target effects, Momentum, Angular)
Missing Mass
Raw Data
Need to do
Data & Info
Lambda&Sigma12ΛBgs Spectra
Geant4 Simulation
HKS Sieve Slit
HES Sieve Slit
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Calibration Procedure of the Spectrometer System
Forward Tuning
Backward tuning
mass spectroscopy
Nonlinear Least Chi2 fitting
Kinematical scan
Initial state
Magnetic field study
Geant4 Simulation Focal plane pattern
Real Data
Λ & Σ mass spectroscopy
Field map
Focal plane pattern
Matching level A
SS pattern SS hole
Matching level
B
Kinematical parameters
Independent level C
matrices
A&B&C
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Forward Optics Tuning
Purple: 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
Purple: Geant4 simulation green: Real HES SS data
Target
Beam Kaon
Q1
Q2
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Forward Optics Tuning
The asymmetry functions are introduced and tuned for HKS&HES quadruple field Bx and By, independently.
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The Mass Status of Forward Optics Tuning
Start Point
after forward tuning 11
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Backward Spectrometer System Calibration
Spectrometer system calibration key : to reach 400 keV energy resolution Common splitter : Separated single arm kinematics and optics calibration is not
possible Technique: 2-arm coupled calibration for both kinematics and optics
Using known masses of, from CH2 target and identified known hypernuclear bound states 12
Bgs for spectrometer calibration
HES spectrometer system
Beam
Target
Splitter
HKSHES
Sieve Slit
To beam dump
12 B (gs)
Kaon Momentum (MeV/c)
Kinematics coverage
Sieve Slit
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Calibration Procedure
(Ebeam , Pk , xt’k, yt’k , Pe, , xt’e, ,yt’e’ )
(1+δ/100)
= =
Mathematical optimization by Nonlinear Least Chi2 fitting
a. Central kinematics scan (mΛ,mΣ,ΔmΛΣ)
b. Angular matrices (mΛ,mΣ,σ)
c. Momentum matrices (12ΛBgs)
d. Iteration
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Preliminary status
Allowing precise calibration of mass scale
0
Λ
p(e, e’K+) and 0 (CH2 target)
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Preliminary status – 12ΛB
E94-107 in Hall A (2003 & 04)
Phase II in Hall C (E01-011)~500
keVFWHM
HKS in 2005
12B
Λ 𝑠 Λ𝑝(E05-115)
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Preliminary status – 10ΛBe
α α
n Λ
α α
p Λ
10BeΛ
10BΛ
-8.38MeV
Cal: 8.84 MeV (without CSB)
Cal: 8.76 MeV (with CSB)
9Be+Λ0 MeV
By E. Hiyama
Preliminary
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Preliminary Result - 7ΛHe
E01011 data
E. Hiyama, et al., PRC53 2078 (1996)
n
n
6He core
3/2+&5/2+
Preliminary E05115
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Preliminary status – 9ΛLi
B = -8.530.18 (emulsion, average over only 8 events)
s
s
s
Sotona and MillenerSaclay-Lyon model for elementary process
s
Ex: 0.0
~0.84
~1.90
~ 2.75
~3.77
~4.38
Hall C HKSE05-115
B = -10.1 0.3
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19
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, Japanese people are still working for it.
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Back Up
Thank you for your attention!
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Online Trigger: (2/3 ()) (WC1WC2) AC (rejecte +> 99%), WC (rejecte p+>99%),
Offline KID: Cuts on number of photon electrons (NPE) Optimize Cutting values – More Kaon(95%), less Pion &Proton
Particle ID
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Experimental Setup-Tilt Method-
Electroproduction differential cross section(Miloslav Sontana)
Г : virtual photon flux Photoproduction cross section by virtual photon
𝑑5𝜎𝑑𝐸𝑒
′ 𝑑Ω𝑒′ 𝑑Ω𝐾
=Γ 𝑑𝜎𝑑Ω𝐾
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7Li target :Physics of (A = 7,T=1)E. Hiyama et al.PRC80,054321(2009)
-5.40 (EXP)
-3.79 (EXP)
Possible Charge Sym. Breaking?
NO Reliable DATA
-4.42
(T=1)
-6.39
-5.40
BΛ=-5.58
7LLi
7LHe
7LB
e
αΛ
n n
αΛ
n p
αΛ p
p
M.Jurič et al., NP B52(1973) 1
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7LHe
α
n
n
Λ
α S
Unbound neutron halo
Bound states
Direct Observation of L’s glue-like role
n
n
NO DATA
Another Physics of HKS-HES (E05-115)
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10B targetMillener’s parameterization(V,D,SN,SL,T)
Hyperball’s g data
α α
n Λ
10BeΛ
α α
p Λ
10BΛ
Imperfect treatment of Tensor force?Bad wavefunction of the core nucleus?
predicts >200keV 1-2- separation
10B(e,e’K)
Cluster Calc. based on the same framework
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Coincident
Time: The correlation of HKS target time and HES target time, give us the coincident spectrum:
Real events
Accidental
Ktar
etarcoin TTT '
PID cut is applied and path length correction has been done
Coincident Trigger Set
HKS :
HKStrigger=(CP)×(K)
CP=(KTOF1X)×(KTOF1Y)×(KTOF2X)
K=WC×
HES:
HEStrigger=(EHODO1)×(EHODO2)
×:AND
COINtrigger=(HKStrigger)×(HEStrigger)