Experiment of Positron Production with Crystal

Experiment of Positron Production
with W Single Crystal(Preliminary Results)

Kazuro Furukawa, KEK<kazuro.furukawa@kek.jp>
forCollaboration group ofS.Anami, A.Enomoto, K.Furukawa, K.Kakihara, T.Kamitani,
H.Okuno, Y.Ogawa, A.Ohsawa, T.Oogoe, T.Suwada [ KEK ],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, 7th ISG, Nov.2001.

Experiment of Positron Production with Crystal

Positron Generationu To Get Higher Yield --- Thicker Target
but Broader Momentum Spectrum--- Lower Capture Efficiency--- Higher Focusing Magnetic Field / Accelerating Field--- Discharge Issues, etc
for Linear Collidersu Higher Incident Energy and thus Higher Positron Yieldu However, Higher Repetition and Larger Number of Bunches
Heating Issues, There are Many Ideas, but ...
u Also Optimization of Thickness and Post Acceleration

K.Furukawa, 7th ISG, Nov.2001.

Experiment of Positron Production with Crystal

Beam Induced Lightu Bremsstrahlungu Channeling Radiationu Cerenkov Radiationu Optical Transition Radiation (OTR), (ODR)
u Synchrotron Orbit Radiation (SOR)u Coherent Bremsstrahlungu etc.
They are used for Beam Instrumentations, etc.

K.Furukawa, 7th ISG, Nov.2001.

Experiment of Positron Production with Crystal

Positron Generation Enhancement byChanneling Radiation and Coherent Bremsstrahlung
Using Single Crystal (Tungsten or Tantalum)u Suggested by R. Chehab et al, (LAL) 1989
u Technical Issues -- Vacuum, Cooling (because of Goniometer)u Thick Crystal Productionu Thickness Dependenceu Incident Energy Dependenceu Mosaicity
u Instant and Integrated Radiation Hardness of Crystalu Crystal / Amorphous Combination Ratiou Simulation Code Development for Positron Generator Design
K.Furukawa, 7th ISG, Nov.2001.

Experiment of Positron Production with Crystal

Channeling and Coherent Bremsstrahlung
CrystalNucleus
ChannelBeam
Channeling Radiationu In single crystal
these two phenomenaenhance e.m. shower
then positron yields
Coherent Bremsstrahlung
K.Furukawa, 7th ISG, Nov.2001.

Experiment of Positron Production with Crystal

Beam Experiment in Japanu INS ES 1GeV (-1999)
u KEK Linac 3-GeV Experiment (1998)
Enhancement Confirmationu KEK Linac 8-GeV Experiment (2000-)More Quantitative Considerations
Collaboration
Tomsk Polytech. --- Crystal Production, Simulation CodeTokyo Metro. Univ., Hiroshima Univ., KEK
Beam Line Construction, Detector Design, Simulation
K.Furukawa, 7th ISG, Nov.2001.

Experiment of Positron Production with Crystal

Experiment Stations
Sector B

Sector A

A-Gun
Positron Source

180-deg.
ArcSector C

C-Gun

Sector 2

Sector 1

ECS
Sector 3Sector 4Beam
Switchyard

KEKB

3-GeV Experimente--GunARC[R0]

Sector 5PF

BCS[17]e+-Target

ECS[61]e--BT(PF)e+-BT(KEKB)
e--BT(KEKB,AR)

8-GeV Experiment
K.Furukawa, 7th ISG, Nov.2001.

Experiment of Positron Production with Crystal

3-GeV Experiment at KEK Linacu Enhancement Measurement (1999)
with 3-GeV 6nC 10ps Beam
u 0.5 Radiation Length (r.l.) Crystal+ 2.0 r.l. Amorphous (r.l. = 3.4mm for Tungsten)
Measured x1.4 Enhancementu No Short-bunch Radiation/Heating Degradation Observed
u Goniometer Radiation Hardness and Vacuum Issues

K.Furukawa, 7th ISG, Nov.2001.

Experiment of Positron Production with Crystal

3-GeV Experiment Apparatus

FWHM~6.9mrad is much Larger than
Channeling-only Lindhard Angle (0.7)
thus Coherent Brems. and Mosaicity
K.Furukawa, 7th ISG, Nov.2001.

Experiment of Positron Production with Crystal

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

K.Furukawa, 7th ISG, Nov.2001.

Experiment of Positron Production with Crystal

8-GeV Experiment Apparatus

Goniometer

Goniometer
Lucite Cerenkov Counter
Lead Glass Cerenkov Counter
K.Furukawa, 7th ISG, Nov.2001.

Experiment of Positron Production with Crystal

K.Furukawa, 7th ISG, Nov.2001.

Experiment of Positron Production with Crystal

K.Furukawa, 7th ISG, Nov.2001.

Experiment of Positron Production with Crystal

Thin Target Scan
0.63 r.l. (2.2mm) Crystal
without Amorphous
x5 Enhancement(for 20MeV e+)upper: Lucite
lower: Lead Glass~9mrad FWHM
Mostly Coherent Brems.

K.Furukawa, 7th ISG, Nov.2001.

Experiment of Positron Production with CrystalAnalysis
u ADC Linearity Study
Small Dynamic Range, Need Careful Gain Control
u Background Analysis
Beam Hitting Upstream Ducts, etc
Lead Shield was Goodu Positron Energy Dependence was Measured
but Positron Loss in Air was not Negligible
Lower Energy e+ Showed Larger Enhancementu Thickness (Amorphous) Dependenceu Crystal Mosaicity Measured with Position Scan of Target
K.Furukawa, 7th ISG, Nov.2001.

Experiment of Positron Production with Crystal

Rocking Curves

FWHM~9mrad, ~20mrad, ~39mrad--> Mostly Coherent Brems.
Need precise sim. codes

K.Furukawa, 7th ISG, Nov.2001.

Experiment of Positron Production with Crystal

Enhancement Factors
Momentum
Enhancement
Enhancement
Enhancement[MeV/c](2.2-mm-thick)(5.3-mm-thick)(9.0-mm-thick)______________________________________________________________________________________
1015
206.56.2
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, 7th ISG, Nov.2001.

Experiment of Positron Production with Crystal

Positron Yields Enhancement

K.Furukawa, 7th ISG, Nov.2001.

Experiment of Positron Production with Crystal(Preliminary) Conclusion
u The Results will be published in NIM soonu Beam Line and Detector Systems Worked Fineu With Thin (2.2 mm) and Thick (9mm) Crystal
5-Times and 1.7-Times Enhancements were Observedu Yield from 9mm Crystal was Larger than 15-28mm Amorphous---> Lower Heat Deposit at Targetu Thickness and Out-going Energy Dependenceu With Lower Positron Momentum, Higher Enhancementu Need Good Simulation Codeu Collaboration with Orsay (Chehab san) Group<URL:http:/ / www-linac.kek.jp/ chan-pos/ >K.Furukawa, 7th ISG, Nov.2001.