ICAR:U of C Activities

Kwang-Je KimSeptember 3, 2003

U of C: KJK• Part A: Ionization cooling theory

– K.-J. Kim and C.-x. Wang (ANL)

• Part. B: Smith-Purcell Laboratory– O. Kapp, A. Crewe,Y.-e Sun (student),Yau Wah

• Part C: Graduate Physics Course “ Accelerator Physics and Technologies for Linear Colliders”– Kwang-Je Kim

• Part D: Participation to flat beam generation experiment at FNPL– Y.-e Sun (student)

Part A: Ionization Cooling Theory

• Theoretical effort by K.-J. Kim and C.-x. Wang

• A comprehensive linear theory for ionization cooling taking into account– Transport in cooling lattice (Hamiltonian)– Dissipation and fluctuation in absorbers– Emittance exchange via dispersion and wedge

absorbers– Beam angular momentum

• Moments expressed in terms of five invariant emittances

Emittance Exchange

Dipole (bend)

+p

0

-p

x xop/pDipole introduces dispersion

Wedge Absorber reduces energy spread

beam

Equation of Motion• Phase space vector

•

•

0

0Tyx p

pp;),z,p,y,p,x( X

motionnHamiltonia;JH,XdsdX

H H

HXX21 TH

MH dsdX

dsdX

dsdX

0100

1000

00010010

J

Hamiltonian of the Focusing System

solenoid + dipole + quadrupole + RF + absorber

dipole quadrupole r.f.

solenoid

,

Lab frame

Rotating frame

, ,,

Emittance Evolution Near Equilibrium Parametrized by Five Invarients

Guidance for developing cooling channel with emittance-exchange

Further Theoretical Topics• Recursive evaluation of beam transport lattice

consisting of extended elements ( such as solenoids used in ionization cooling channels)

• Rigorous treatment of magnetic field expansion for curved reference orbits…Provided bench-marking of ICOOL

• Extensive Publications including two PRLs

Selected papers on related developments• C.-x. Wang and K.-J. Kim, COOL03, NIM A (2003) Beam envelope theory of ionization cooling• C.-x. Wang and K.-J. Kim, PRL 88(18) 184801 (2002) Linear Theory of Ionization Cooling in 6D Phase Space• C.-x. Wang and K.-J. Kim, NIM A503 401 (2001) Linear theory of transverse and longitudinal cooling in a quad. channel• C.-x. Wang and K.-J. Kim, PRE 63 056502 (2001) Recursive solution for beam dynamics of periodic focusing channels• C.-x. Wang, NIM A503 409 (2001) Dispersions in a bent-solenoid channel• C.-x. Wang and L.C. Teng, PAC’01(2001) Magnetic Field Expansion in a Bent-Solenoid Channel• K.-J. Kim and C.-x. Wang, NIM A472 561(2001) Progress in the Linear Beam Dynamics Study of Ionization Cooling Channel• K.-J. Kim and C.-x. Wang, PRL 85(4) 760 (2000) Formulas for Transverse Ionization Cooling in Solenoidal Channels

Part B: Smith-Purcell Laboratory

• An electron microscope–based Smith-Purcell generator for a compact far IR source

• Retrofitted the sample chamber of a Cambridge S-200 scanning electron microscope with a grating

• Radiation transported via a polyethyene window to a bolometer

• Observed spontaneous Smith-Purcell radiation after carefully eliminating the effects due to blackbody radiation. (c.f., Dartmouth claim on high-gain behavior)

• We are evaluating:– Several options for electron sources (heated tungsten tip, Lab6,

Thermionic field emission)– Electron beam recovery system

• Preparing proposals for other funding agencies

Part C: A Graduate Physics Course “ Physics and Technologies for Linear

Colliders

• Physics 575 during winter 2002

• Lectures by experts in the field– S. Holmes, K.J. Kim, T. Raubenheimer, J.

Rosenzweig, L. Emery, J. Wang, L. Lilje, F. Zimmermann, V. Shiltsev, W. Gai

• Lecture notes in the course web page– http://hep.uchicago.edu/~kwangje/phy575.html

Part D: Flat Beam Generation

• A novel beam manipulation technique proposed by Y.Derbenev

• A flat beam ratio (FBR) of 50 has been achieved at FNPL ( FNAL-NIU Photocathode Laboratory).

• Yin-e Sun is investigating effects reducing FBR– Energy spread, space-charge effects, breaking of cylindrical

symmetry• To improve the flat beam ratio to >100.

Schematic rendition of the layout at Fermilabfor flat beam experiment

x = A cos z

y = A sin z

A cos z

A sin (z+/2)

flat beamvortex beam

FermiLab/NICADD PhotoInjector

Layout taken from PAC01 paper of D. Edwards etc.

Flat electron beam profile at 9.6m from the cathode (XL6) and horizontal and vertical beamlets used for emittance measurements downstream at XL7 and XL8. The transverse emittance ratio is about 41 in the example shown here.

4195.085.38

mradmmmradmm

xn

yn

Major Budget Items• Part A… Fund transfer to ANL to support C.-x.

Wang• Part B …Partial (40-50%) salary support for O.

Kapp, equipments and supplies, technician charges

• Part C…Travel support for lecturers• Part D…Stipend for a graduate student• Domestic and international travels