Outline:• 1) Experiment Setup• 2) HES Geant4 Simulation • 3) Missing Mass Spectra Calibration• 4) Experiment status

Zhihong Ye, March 16th 2009HU Group Meeting

2.5 GeVElectron beam

1.5 GeV K+

HES

HKS

E05-115 E05-115 0.844 GeV e’

Splitter + Target

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Using HKS-HES Geant4 code to generate ‘real’ physics events, idea optics events (no physics effects, no detector resolutions), and sieve slit events (with sieve slit planes for both HKS and HES).

‘Real’ physics events Five targets : Polyethylene (Λ & Σ), 7Li (7

ΛHe), 12C (12 ΛB), 28Si (28

ΛAl), 52Cr(52 ΛV)

States: (G.S – Ground State, F# - Fake state, S# - Spin Flip sub state)

Λ, Σ(+76.965Mev), Quasi-free (from Carbon), Accidental 12

ΛB : G.S., F1 (+3Mev), F2 (+6Mev), F3(+10Mev) S1(+140Kev), S2(+10Mev+70Kev), Accidental

28 ΛAl : G.S, F1 (+6Mev), F2 (+12Mev), F3(+18Mev)

S1(+110Kev), S2(+6Mev+220Kev), Accidental

52 ΛV: G.S., F1 (+6Mev), F2 (+12Mev), F3(+18Mev)

S1(+80Kev), S2(+12Mev+320Mev), Accidental

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=0.0934mrad =0.112mrad =0.00289%

=0.0335mrad=0.209mrad

=00262%

Introduce detectors’ angular and position resolutions for HKS and HES focus planes, base on last experiment and HES design:

HES: x = 0.007 cm, y =0.015 cm, x' = 0.5 mrad, y' = 0.9 mradHKS: x = 0.015 cm, y =0.015 cm, x' = 0.3 mrad, y' = 0.3 mrad

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6

7

Λ

Σ

Sieve Slit Data I Added sieve slit planes and generated physics events using Carb

on Target. Then I used defected matrices to reconstruct them back to target planes, and sent the data again into Geant codes.

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HES Sieve Slit HKS Sieve Slit

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a) Major Idea The source of missing mass spectra deviation are: 1, Accuracy of spectrometers installation (Optics), and 2, Centre momentum and angle offsets, beam energy accuracy (Kinematics).

Normally we use single optics matrix to describe the whole spectroscopy system, and also absorb the effect kinematics misunderstanding. For our case –

One kinematics; No calibration data on Sieve slit; Five missing mass with independent kinematics effect.

b) Optics

Two complete new optics systems: Splitter + HKS, and Splitter + HES.

c) Kinematics offset I purposely introduce certain offset for center momentum, beam energy and

center angle, when I do the missing mass calculation. For example: ΔE0 = 1 MeV, ΔPk = 1 MeV, ΔPe = 1 MeV ΔEX’ = 3 mrad, ΔEY’ = 3 mrad, ΔKX’ = 3 mrad, ΔKY’ = 3 mrad

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HKS / HES Optics System

Mathematically: fpsssst xMxxMx 12

11 ,)()()(

Or fpfpt xMMxMx )()()()()()( 12

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1

So Sieve Slit data calibration will get us the matrices of HKS and HES, which is nothing to do with Splitter matrix. And we can use Geant simulation to get the initial matrix of splitter and use Lambda and Sigma data to get the real matrix.

There are two separate procedures!

The graphics show the contribution of optics and kinematics effect on bounding energy and resolution for different hypernuclei :

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B.E. offset: Momentum and beam energy offset is the major contribution, and the effect increases as mass increase. Optics and center angle offset show little effects.

Resolution;

Optics (Defected matrix) is the major source. The contribution of center angle offset reduce when the mass goes higher.

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Optics and kinematics calibrations are two separately procedure and can be treated independently.

Two Chi-Squares are defined to do offset scanning:

Mathematically, these two Chi-Squares both represent the deviation of missing mass spectra, respected to kinematics offsets

We deal with it separately:

Momentum&E0:Angle:

To solve those parameters, we need three or four Bounding Conditions. Besides Lambda and Sigma, we included 7

ΛHe and 12

ΛB into the calibration.

PePe

MMPk

Pk

MME

E

MM

KYKY

MMKX

KX

MMEY

EY

MMEX

EX

MM

PePkEKYKXEYEXfMM

00

0

''

''

''

''

),,,',',','(

)',',','( KYKXEYEXgMM ),,( 0 PePkEhMM

2_

20

2 /)(,)/( widthsigmafitoffsetMeanfitwidth xxx

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)'','','',''(')',',','( dKyKydKxKxdEyEydExExgdKydKxdEydExang

),,('),,( 0 dPePedPkPkdEEhdPedPkdEmom

12/4

7/3/2/1

//

Bwidthoffset

Hewidthoffsetwidthoffsetwidthoffset

angmomwidthoffset

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Currently, Testing EDCs, KDCs, Aeroger Cerenkov and Water Cerenkov detectors, Hodoscopes, Water Target in EEL Building. Calibration procedure study using Geant4 Code. Preparing Online and offline analysis codes. March, 2009 Start to install HKS and HES detector packages in Hall C after SANE experiment finishes.

August 16th, 2009 ~ October 16th, 2009 (May extended) Start taking experiment data.

I need to do: Doing optics calibration using Sieve Slit data; Finalizing kinematics calibration procedure; helping other students to test and install detectors.