Positron Production Experiment with Crystal

Positron Production Experimentwith Single Crystal(Preliminary Results)[1st. Part: for KEK Exp.][2nd. Part: for CERN Exp. (in Separate Presentation)]
Kazuro Furukawa, KEK<kazuro.furukawa@kek.jp>
forCollaboration group of
S.Anami, A.Enomoto, K.Furukawa, K.Kakihara, T.Kamitani,
H.Okuno, Y.Ogawa, A.Ohsawa, T.Oogoe, T.Suwada [ KEK ],R.Chehab [LAL, Orsay],
R.Hamatsu, K.Sasahara [ Tokyo Metro. Univ. ],T.Fujita, K.Umemori, K.Yoshida [ Hiroshima Univ. ],V.Ababiy, A.P.Potylitsin, I.E.Vnukov [ Tomsk Polytech. ]<URL:http://www-linac.kek.jp/chan-pos/>

K.Furukawa, LC2002, Feb.2002.

Positron Production Experiment with Crystal

Positron Generation Enhancement byChanneling Radiation and Coherent Bremsstrahlung
Using Single Crystal (Tungsten or Diamond)◆ Suggested by R. Chehab (LAL) et al, 1989
◆ Technical Issues -- Vacuum, Cooling (because of Goniometer)◆ Thick Crystal Production◆ Thickness Dependence◆ Incident and Outgoing Energy Dependence◆ Mosaicity◆ Instant and Integrated Radiation Hardness of Crystal◆ Composite Target (Crystal/Amorphous, Diamond+Tungsten)◆ Simulation Code Development for Positron Generator Design(GEANT+Channeling, Fast Code, Heating, e+ Capturing)
K.Furukawa, LC2002, Feb.2002.

Positron Production Experiment with Crystal

Channeling and Coherent Bremsstrahlung
CrystalNucleus
ChannelBeamChanneling Radiation◆ In single crystal
these two phenomenaenhance e.m. shower(photon) and positron yields
Coherent Bremsstrahlung
K.Furukawa, LC2002, Feb.2002.

Positron Production Experiment with Crystal

Beam Experiment in Japan◆ INS ES 1GeV (-1999)◆ KEK Linac 3-GeV Experiment (1998)
Enhancement Confirmation◆ KEK Linac 8-GeV/4-GeV Experiment (2000-)More Quantitative Considerations
Collaboration
Tomsk Polytech. --- Crystal Production, Simulation CodeTokyo Metro. Univ., Hiroshima Univ., KEK
Beam Line Construction, Detector Design, Simulation
R. Chehab --- Ideas, etc.
K.Furukawa, LC2002, Feb.2002.

Positron Production Experiment with Crystal

Experiment Stations
Sector B

Sector A

A-Gun
Positron Source

180-deg.
ArcSector C

C-Gun

Sector 2

Sector 1

ECS
Sector 3

Sector 4

e--GunSector 5

BeamSwitchyardPF
KEKB

3-GeV Experiment

ARC[R0]ECS[61]e+-Targete--BT(PF)e+-BT(KEKB)
e--BT(KEKB,PFAR)4, 8-GeV Experiment
K.Furukawa, LC2002, Feb.2002.

Positron Production Experiment with Crystal

8 and 4 -GeV Experiment at KEK Linac◆ Analyzer Line at the End of Linac
No Direct Interference against KEKB, PF, PFAR Operation◆ 8-GeV 0.2nC (~1x109) 10ps
◆ 2.2mm (=0.63 Radiation Length (r.l.)) Crystal(r.l. = 3.4mm for Tungsten)
Then 5.3mm, 9.0mm Thick Crystal
Measured Enhancement◆ 4-GeV - 2.2mm, 5.3mm, 9.0mm Crystals
Also 1.1mm Diamond

K.Furukawa, LC2002, Feb.2002.

Positron Production Experiment with Crystal

8 and 4 -GeV Experiment Apparatus

Goniometer∆p/p ~ 3.0%, ∆θ ~ 20mrad
Goniometer
Lucite Cerenkov Counter
Lead Glass Cerenkov Counter
K.Furukawa, LC2002, Feb.2002.

Positron Production Experiment with Crystal

K.Furukawa, LC2002, Feb.2002.

Positron Production Experiment with Crystal

Rocking Curves (8GeV)

2.2mm, 5.3mm, 9mm W Crystal
FWHM~9mrad, ~20mrad, ~39mrad

K.Furukawa, LC2002, Feb.2002.

Positron Production Experiment with Crystal

Enhancement Factors (8GeV)
Outgoing e+
Momentum
Enhancement
Enhancement
Enhancement[MeV/c](2.2-mm-thick)(5.3-mm-thick)(9.0-mm-thick)______________________________________________________________________________________
1015
20

6.5
6.2
5.1

0.6
0.8
0.5

3.4
3.2
3.0

0.7
0.5
0.5

2.3 0.4
2.0 0.2
1.8 0.2

K.Furukawa, LC2002, Feb.2002.

Positron Production Experiment with Crystal

Positron Yields Enhancement (8GeV)
Crystal Exp.

Amorphous Exp.
and Calc.

Positron Production
vs. Thickness
Out-going Positron Momentum
10, 15, 20 MeV/c

9mm Crystal Generates More e+than Thick Amorphous
K.Furukawa, LC2002, Feb.2002.

Positron Production Experiment with Crystal

Positron Enhancement with 4GeV Incident Beam◆ 2.2, 5.3, 9 mm-thick Tungsten Crystal and Amorphous(Preliminary Analysis)
700

4-GeV Wcrystal
P=20MeV/c

Positron Yield [arb. unit]

600

500

400300Wcron-20MeV
Wcroff-20MeV
Wa-20MeV
Wref-20MeV

200

1000051015202530

Thickness of W in Total [mm]K.Furukawa, LC2002, Feb.2002.

Positron Production Experiment with Crystal

Positron Enhancement with 4GeV and 8GeV
◆ 2.2, 5.3, 9 mm-thick Tungsten Crystal and Amorphous(Preliminary Analysis)668-GeV Wcrystal

4-GeV Wcrystal
Pe+=10MeV/c

54Enhancement

Enhancement

52.2mm Wcr&W
5.3mm Wcr&W
9mm Wcr&W

Pe+=20MeV/c

2.2mmWcr
5.3mmWcr
9mmWcr3432211000510152025

Thickness of W in Total [mm]30051015202530

Thickness of W in Total [mm]◆ Most Enhancement Occurs in the First millimeter
K.Furukawa, LC2002, Feb.2002.

Positron Production Experiment with Crystal

Optimal Thickness and Brightness
Theoretical Work
by V.N.Baier, V.M.Katkov,and V.M.Strakhovenko
Phys. Stat. Sol. 133(1986)583◆ Optimal Thickness
Thickness of satulated
radiation brightness

C(d)

15.6

W(293K)0.65(at 1GeV, Energy dependence is small)◆ Brightness
at Optimal Thickness
Diamond Produces
3-Times Larger
Radiation thanTungsten
K.Furukawa, LC2002, Feb.2002.

Positron Production Experiment with Crystal

Diamond Target and Positron Enhancement◆ 1.1mm-thick Diamond + TungstenDiamond as Photon Emitter, Tungsten as Pair Producer◆ at 4 GeV and 8 GeV (Preliminary Analysis)◆ Far from Optimal Thickness (We need 10mm Diamond)
8Diamond.data
7Enhacement@ 4GeVEnhacement

6Enhacement@ 8GeV
5432

10

5

101520Thickness of Amorphous W[mm]K.Furukawa, LC2002, Feb.2002.

Positron Production Experiment with Crystal

Heating◆ Simulation by R.Chehab, et.al
Particle Accelerators 59(1998)19◆ 21mm Amorphous, 8mm Crystal,
4mm Crystal + 4mm Amorphouse- for 5x1011 BeamPowere+ at IP(kW)

Target Power Target Peak(kW)Temp. (°C)

8mm W(crys.)
4mm W(crys.)+ 4mm W(amor.)

5x10115x1011

120
120

6.6
6.7

1400
489(crys.)2184(amor.)

21mm W(amor.)

3.3x1011

79

27.0

2102

4mmW(crys.)
489°C

10GeV 150Hz, JLC(1995)-like System Assumed

4mmW(amor.)
2184°C

K.Furukawa, LC2002, Feb.2002.

Positron Production Experiment with Crystal

Summary◆ Positron Production Enhancement with W Crystal was Measured
Dependencies on
Incident Energy (4, 8 GeV),
Target Thickness (2.2, 5.3, 9, etc mm)
Out-going Positron Energy (5,10,15,20 MeV)

◆ With Thin (2.2 mm) Crystal 5-Times Enhancement was Observed◆ Yield from 9mm Crystal was Larger than 15-28mm Amorphous◆ The Results will Help Refining Simulation Codes◆ Diamond Compound (Thick Diamond+Tungsten) Target
May be promising◆ Need More Heating Simulation
K.Furukawa, LC2002, Feb.2002.

Positron Production Experiment with Crystal

K.Furukawa, LC2002, Feb.2002.