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

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

Experimental Setup

Splitter Magnet

HKS

HES

Bremsstralung flux

Virtual photon flux factor

K+

e’

e

PreChicane-SPL-(HKS+HES) Configuration

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

Experimental Setup -Detector Package-

HES-D

e’

EHOD2

EHOD1

EDC2EDC1

HES Detectors

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

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

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

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 11

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

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

Preliminary status

Allowing precise calibration of mass scale

0

Λ

p(e, e’K+) and 0 (CH2 target)

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)

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

Preliminary Result - 7ΛHe

E01011 data

E. Hiyama, et al., PRC53 2078 (1996)

n

n

6He core

3/2+&5/2+

Preliminary E05115

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

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.

Back Up

Thank you for your attention!

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

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

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

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)

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

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)