E01-011 Analysis updateAdjust of the Splitter-HKS Side

Yuncheng HanMay 09, 2012

Hampton UniversityJLab hypernuclear collaboration meeting

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Outline

• Overview of the E01-011 experiment• Principle of the forward optics tune• Methods of the optical matrix modification• Further optimize the optical matrices from

focal plane to sieve slit plane• Status using the new optical matrices

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Overview of the E01-011 ExperimentCarried out at JLab in 2005, to obtain high resolution, high yield rates hypernuclear spectroscopy, for study of hyperon-nucleon interaction.

e + p → / 0+ e’+ K+

Target N

e + N → N + e’+ K+

e

γ*

e’

K+

p

/0

Three generations : E89-009 (2000), E01-011 (2005), E05-115(2009)

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The Results of E01-011 Experiment-6.730.02 0.2 MeV

7He

FWHM ~500 keV

12B

12B : consistent of JLab E89-009;

much better resolution.

28Al :1st medium-heavy hyper-nuclear

spectrum w/ clear s-, p-, d-shell state peaks; space of s- and p- shell states 1~2 MeV wider but p- and d- shell states ~1 MeV narrower than expected

7He: 1st time w/ high statistics;

BΛ and feature confirmed;Paper drafted: n-halo state, CSB.

B (MeV)

HKSJLAB

Cou

nts

(150

keV

/bin

)

s

p d

28Al

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The Status of E01-011 Experiment

• Data analysis was already done, 7He, 12

B, 28Al;

• However, the splitter magnet actual current in this exp was 8.5 % bigger than the designed value, which made the real optics different a lot from the designed one. The previous analysis used the designed optics as an initial, and relying on mathematical method (nonlinear χ2 fit ) for optimization;

• Freedom of the mathematical tune is large (1260 elements in the optics matrices), so the reliability of the final results was not solid;

• Since the fringe field near the splitter magnet region introduce asymmetry to the magnetic field map, a better optics can be gotten if consider the asymmetry.

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Previous analysis method

Nonlinear least χ2 fittingkinematical scan

Geant3

CH2 data

Λ & Σ0 mass spectroscopy

Field map

Kinematics: masses and emit angles of Λ & Σ0

Mathematical tune of optics matrices

Initialoptics matrices

Tuned matrices

Exp. data

Backward tune

Λ-hypernuclear spectroscopy

Final matrices

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New Analysis method

Magnetic field study

Geant3 simulation Sim focal plane distribution

Exp data

Calculated Λ/Σ spectroscopy

Field map

A

Reconstructedsieve slit distri

B

Mass/angle independence

C

Qualifications of A, B and C

Optical matrices Exp focal plane distribution

Sieve slitgeometry

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Relationship between sieve slit and focal plane

Target SplitterSieveSlit Q1-Q2-Dipole

Focal Plane K+

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• New optical matrices was introduced to satisfy Focal plane distribution sim match exp data Reconstructed sieve slit distribution match real sieve slit geometry Calculated masses independent on kinematical parameters of kaons (p, X’, Y’)

• New optical matrices was gotten by Introduce asymmetry function to the magnetic field map offset of the field map geometry Adjust position of focal plane

Strategy of introduce new opticsTarget Splitter Sieve

SlitQ1-Q2-Dipole Focal

Plane K+

Focal plane position 235 cm to 265 cmChambers’ distance 100 cm to 36 cm

Splitter asymmetry

Q1 asymmetry

Q2 asymmetry

Dipole asymmetry

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FP X’-X FP Y-X Sieve Slit

Comparison of focal plane/sieve slit distribution

W/ initial optical matrices

W/ new optical matrices

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Comparison of mass dependence on kinematics

W/ initial optical matrices

W/ new optical matrices

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Region of one hole Center of the hole (X-X0)2 + (Y-Y0)2 < R2 (X0,Y0)

Further optimize the optical matrices

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Masses and emit angles of Λ/ w/ new matrices

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W/ initial optical matrices

W/ new optical matrices

Comparison of Λ/0 mass spectrum

Mathematical method (nonlinear least χ2 fit )

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12B

Δ ~ 10.79 MeV

Δ ~ 11.64 MeV

Δ ~ 10.97 MeV

Δ ~ 11.05 MeV

Comparison of 12B mass spectrum

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Summary• E01-011 experiment was carried out in 2005 at JLab, analysis was

already done, 7He, 12

B, 28Al;

• Initial optical matrices was poor, by introduce scaling asymmetry function, offset field map geometry, and adjust position of focal plane, new optical matrices for Splitter-HKS side was obtained;

• Quality of Λ/0 spectrum w/ new optical matrices is already comparable of previous finalized results;

• 12B mass spectrum was checked w/ new optical matrices ;

• New optical matrices for electron arm will be tune soon• More reliable and higher quality results are expected with the new

optical matrices (for both electron arm and kaon arm) and the powerful nonlinear least χ2 fit mathematical tune.

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Residual of present optical matrices