Polarized Positron Experiment at KEK-ATF
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Polarized Positron Experiment at KEK-ATF. JPSMeeting2005. KEK ATF におけるパルス偏極陽電子生成3 〜 偏極陽電子生成とその偏極度測定 〜. 浦川順治、 @ 大森恒彦、奥木敏行、栗原良将、 黒田隆之助 A 、斉藤卓 A 、坂上和之 A 、広瀬立成 A 、 福田将史 B 、鷲尾方一 A. 高エ研、早大理工総研 A 、放医研 B. Pol. e + Production. Design values. N g = 1 x 10 7 /bunch.

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Polarized positron experiment at kek atf

Polarized Positron Experiment at KEK-ATF

JPSMeeting2005

KEKATFにおけるパルス偏極陽電子生成3

〜偏極陽電子生成とその偏極度測定〜

[email protected]

黒田隆之助A、斉藤卓A、坂上和之A、広瀬立成A、

福田将史B、鷲尾方一A

高エ研、早大理工総研A、放医研B


Polarized positron experiment at kek atf

Pol. e+ Production

Design values

Ng = 1 x 107 /bunch

Ne+ = 1 x 104/bunch (Ee+ = 25 to 45 MeV)

Pol. e+ ~ 80 %

DT(rms) = 31 psec

Can NOT measure each e+

Polarimetry ?


Polarized positron experiment at kek atf

Measure e+ polarization :

use Bremsstrahlung g-ray

g-ray

polarized e+

E = 40 MeV

Pb conveter


Polarized positron experiment at kek atf

Measurement and Cross-Check

Measurement

e+ beam pol.

(laser pol)

e- spin in iron

(magnet pol.)

expected value

(MC)

)

Calculate A

R

A(R) : A(R)= ~ + 0.7 %

)

Calculate A

A(L) : A(L)= ~ - 0.7 %

L

)

Calculate A

0

non (Liner)

A(0) : A(0)=0

Cross-Check

e+ beam pol.

magnet pol.

)

Calculate A

A(P) : A(P)= ~ + 0.7 %

P

)

N

A(N) : A(N)= ~ - 0.7 %

Calculate A

Zero magnet current Not Equal No-polarization,

due to residual magnetism


Polarized positron experiment at kek atf

Leakage B Feild e+ trajectry Acceptance

Mag. Pol. = P

e+

CO2 Cherenkov

If e+ beam go just center of magnet -> OK

Mag. Pol. = N

e+

CO2 Cherenkov


Polarized positron experiment at kek atf

Leakage B Feild e+ trajectry Acceptance

Mag. Pol. = P

e+

CO2 Cherenkov

If e+ beam go off center, trajectry near magnet

may be

different when we flip magnet.

Mag. Pol. = N

e+

CO2 Cherenkov


Polarized positron experiment at kek atf

A(TP,TN) = 0 acceptance affected by B field

Acceptance Correction

Define: A(TP,TN) = (TP-TN)/(TP+TN)

magnet pol.

e+ beam pol.

)

P

average transmission TP

non

)

N

average transmission TN

non

A(TP,TN) = 0 from absorption in iron

Use A(TP,TN) for acceptance correction


Polarized positron experiment at kek atf

e+ polarization (e+ run): results

preliminary

Measurement

e+ beam pol.

magnet pol.

)

R

A(R)= +0.16± 0.28%

)

L

A(L)= -1.63± 0.28%

)

non (Liner)

A(0)= -0.24± 0.28%

0

Cross-Check

e+ baem pol.

magnet pol.

)

P

A(P)= +0.85± 0.28%

)

A(N)= -0.93± 0.28%

N

Acceptance Correction

A(TP,TN) = -0.57± 0.17%


Polarized positron experiment at kek atf

e+ polarization (e+ run): results

preliminary

Measurement

Acceptance Corrected by A(TP,TN)

e+ beam pol.

magnet pol.

)

R

A(R)= +0.72± 0.28%

)

A(L)= -1.07± 0.28%

L

)

A(0)= +0.33± 0.28%

0

non (Liner)

Cross-Check

e+ beam pol.

magnet pol.

)

P

A(P)= +0.85± 0.28%

)

A(N)= -0.93± 0.28%

N


Polarized positron experiment at kek atf

e+ polarization (e+ run)

preliminary results

e+ beam spin

e- spin in Iron

A(R)= +0.72± 0.28%

e+ beam spin

e- spin in Iron

A(L)= -1.07± 0.28%

e+ beam spin

non

e- spin in Iron

A(0)= +0.33± 0.28%


Polarized positron experiment at kek atf

We did e- run, also.

e- run

e+ run


Polarized positron experiment at kek atf

e-polarization (e- run): results

Measurement

preliminary

e- beam pol.

magnet pol.

)

R

A(R)= +0.81± 0.28%

)

L

A(L)= -0.91± 0.27%

)

non (Liner)

0

A(0)= -0.26± 0.27%

Cross-Check

e- beam pol.

magnet pol.

)

P

A(P)= +0.76± 0.27%

)

A(N)= -0.96± 0.27%

N

Acceptance Correction

A(TP,TN) = -0.12± 0.16%

NO correction is necessary


Polarized positron experiment at kek atf

e- polarization (e- run)

preliminary results

e- beam spin

e- spin in Iron

A(R)= +0.81± 0.28%

e- beam spin

e- spin in Iron

A(L)= -0.91± 0.27%

e- beam spin

non

e- spin in Iron

A(0)= -0.26± 0.27%


Polarized positron experiment at kek atf

Polarized Positron Experiment at KEK-ATF

JPSMeeting2005

まとめ

レーザー光の偏極が、γ線へ、そして対生成された e+と e- へと伝達されていく事が確認された。

2) 短パルス高強度の偏極γ線、e+、e-の偏極測定法が確立できた。

3) 陽電子の透過率のアシンメトリーは予想値である~ 0.7 %に一致した。

--> 偏極度 ~80% の陽電子ビームが得られた。


Polarized positron experiment at kek atf

ここで終わり。

これから後はバックアップ


Polarized positron experiment at kek atf

[email protected]

DT = 31 p sec.

DT = 31 p sec.

DT = 31 p sec.

i) proof-of-principle demonstrations

ii) accumulate technical informations:

polarimetry, beam diagnosis, …


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