HES-HKS & KaoS meeting

Toshi Gogami

Contents

Energy loss simulation by HES,HKS and POSI

1. POSI for beam energy loss– Harver foil is already implemented in this code.– Implemented Raster newly.

2. HKS, HES for K+ and e’ energy loss– Transplant harver foil into these code from POSI.

• バグだし(HES、 HKS)変数の定義の間違え・・・昔からあるようだが。。(POSI)Rasterを入れる際のバグ… .etc

• New ver. GEANT では動かない問題 (HES,HKS)コンストラクターの引数の数、順番G4ThreeVector…..etc日本で解決済

Beam Energy Loss study

Used Geant4 simulation code “Modified POSI”Water ( + harver ) target in the display

Virtual Detector

TargetGeneration point(Uniform in z-direction)

SIMULATION

Momentum distribution

Incident beam

After target

H2O (500mg/cm2)+ Harver

Determination of the value of energy loss

This edge is the peak value which is derived by the fitting results

EDGE

31 keV

Boron , 56.1 mg/cm2

Water target with Harver foils

EDGE

371 keV

Harver foil effect Water

water

Foil

Simulation ResultsTarget < 5 MeV < 1 MeV < 0.5 MeV Kawama Toshi7Li184 mg/cm2

160137165

141121157

133115149

133133151

10389118

9Be188.1 mg/cm2

161141170

140122159

132115150

177 (Chen)177138

10590124

10B56.1 mg/cm2

554855

474052

453950

454552

312737

12C112.5 mg/cm2

11197111

9482105

8977100

9089103

665877

52Cr154 mg/cm2

151140127

113101117

10493112

939499

797188

Water + Harver500 mg/cm2

552555547

429434468

251257254

439*1.6442*1.6487*1.6

371373408

Polyethylene450.8 mg/cm2

500436530

406362454

240241244

436*0.8440*0.8502*0.8

349296416

Unit : keV

Energy Loss scan

• CH2 energy loss ± 20%– How does it effect on the Missing mass– To be reported next week

Λ cross section from water target

Λ cross section from water target

Sensitive Nonlinear Iterative Peak (SNIP) clipping algorithm

References:C. G Ryan et al.: SNIP, a statistics-sensitive background treatment for the quantitative analysis of PIXE spectra in geoscience applications. NIM, B34 (1988), 396-402.M. Morháč, J. Kliman, V. Matoušek, M. Veselský, I. Turzo: Background elimination methods for multidimensional gamma-ray spectra. NIM, A401 (1997) 113-132.D. D. Burgess, R. J. Tervo: Background estimation for gamma-ray spectroscopy. NIM 214 (1983), 431-434.

New Cut efficiency estimation(WC for demonstration)

Real distributionProbability density function (PDF)Imitation dataCut efficiency

K+

p

Nor

mal

ized

N.P

.E

Mass square [GeV/c2]2

Mass square

Mass square [GeV/c2]2

Nor

mal

ized

N.P

.E Water target

Normalized N.P.E

Normalized N.P.E

Mas

s squ

are

[GeV

/c2 ]2 Water target

Seems working well.

Summary and To do• Summary– Energy loss are estimated

• Smaller than those of Kawama-san• Seeing effect on missing mass when the energy loss is changed ±

20%.– Now cut efficiency estimation method ( KID )

• On progress

• To do– Λ cross section from H2O before leaving Germany.– Matrix tuning

• Better cut• Water • TSpectrum Background subtraction• Definition of chi-square