nlc - the next linear collider project sheppard/pitthan july 14, 2015 power meeting june 8=9,2002...

NLC - The Next Linear Collider Project

Sheppard/Pitthan April 19, 2023

POWER MeetingPOWER MeetingJune 8=9,2002June 8=9,2002

Durham, EnglandDurham, England

IP Beam Instrumentation, SLAC Wednesday June 26, 2002

R. Pitthan and J. Sheppard

Sheppard/PitthanApril 19, 20232


First Meeting: June 8-9, 2000

Ushaw College, Durham, England

Sponsored by: Institute of Particle Physics Phenomenology (IPPP), Unversity of Durham (UK)

Organized by: Gudrit Moortgat-Pick, DESY

http://www.desy.de/~gudrid/power.html



• Collection of theorists, experimentalists, accelerator folks

• Did not discuss electron polarization; it’s in the bag

• Positron polarization looks feasible in the range of 40%-70% polarization

• Daresbury to prototype TESLA helical undulator, 3 year time frame, funding limited

•TESLA having difficulty developing a scheme for post-collision polarimetry (Schuler)

•Polarized positron demonstration at FFTB needs polarimetry

•See http://www.desy.de/~gudrid/power.html for talks

Interesting Points



Contacts

Roger Carr, SSRL

Max Cornacchia, SSRL

Ralph Nelson, SLAC RP

Roman Tatchyn, SSRL

Helmut Wiedemann, SSRL

Klaus Flöttmann, DESY

Alexander Mikhailichenko, Cornell

Yuri Batygin, SLAC NLC

Vinod Bharadwaj, SLAC LCLS/NLC

Artem Kulikov, SLAC PEPII

David Schultz, SLAC NLC

Maria Caturla, LLNL

Werner Stein, LLNL



Concepts



• Put development of NLC conventional e+ source on hold

• Use resources to investigate the feasibility of a polarized positron source for the NLC

• Look into the use of a K1 helical undulator and 150 GeV NLC primary electron beam for polarized positron production

• Because of drawback of coupling e+ production to primary e-, investigate other options:

•back scattered laser (Compton)

•short-period novel undulator on dedicated beam

Change in Direction of NLC Positron Effort



NLC Polarized Positron System Layout



NLC Polarized Positron Target Station Layout



Codes: MatLab files, EGS4-Pol, BeamPath

Undulator: K1, u = 1.4-0.7 cm, helical

Search for Optimization: Eb, u, K, target material and thickness, collection scheme

Photon Beam Specification

Target Studies: Ti-alloy: hydro and radiation damage study launched at LLNL

Effect on primary electron beam, studies begun; commissioning and operating scenarios

Open also to Compton based photon sources (lasers and FELs)

What’s Going On? What’s the Status?



We had a discussion at LC02 to explore the possibilities of using a microundulator and the damped, 50 GeV SLAC beam in the FFTB to study positron production. Expectedly warm response from all e+ folks

Use of a Microundulator to Study Positron Production



Use the SLAC 50 GeV, low emittance beam in conjunction with a 1-2 mm period helical undulator to demonstrate undulator based production of polarized positrons for linear collidersMeasure the yield, spectrum, and polarization of both the photons and positrons

An Immodest Proposal

Do this in the next 22-42(?) months in the FFTB enclosure:•Proof of Principle Demonstration•Validate Codes•Develop Spin Diagnostics•Develop e+ Spin Diagnostics

•Maybe Get a Surprise (better not)



What’s the Big Idea?

Goals:Goals: • demonstrate the viability of undulator based positron

production, both polarized and unpolarized • measure the yield, spectrum, and polarization

gammas and positrons.• design (steal, borrow) conversion, collection, and

detection systems• validate the microundulator-photon production codes

Many opportunities for collaboration amongst collider laboratories, and including experimenters from both the colliding physics and the fixed target physics communities who are experts in polarimetry. Efforts for the development of such a collaboration underway.



FFTB Beams

Size <50 m to thread through a narrow sub-mm-gap undulator

• Divergence < 1/

Critical parameters in red



Positron Polarization as a Function of Positron Energy



Positron Spectra for Different Ti Target Lengths



Positron Polarization for Different Ti Lengths



What Does the Hardware Look Like?



A fully modeled experiment which simulates results and identifies hardware

requirements

• Beam line design to determine accelerator hardware specifications

• Cost and schedule development

• Acceptance of proposal and release of funds

• Construction, Installation, Checkout, and Commissioning

• Do experiment and compare with simulations

What is Required



2.4 mm 0 SC, bifilar helical undulator prototype: A. Mikhailichenko

Cornell Univ., 5/21/02



2.4 mm 0 SC, bifilar helical undulator prototype: A. Mikhailichenko




2.4 mm 0 Pulsed Cu helical undulator prototype: A. Mikhailichenko




Experimental Anchor Point Needed

•Since there is no experimental data on polarization (or loss) in scattering, propose a Testbeam Experiment in Sector 0 (the “Ladder” Experiment): Scatter the SLAC polarized electron e-

beams by different r.l. Ti targets, measure relative polarization in the E-158 Møller Spectrometer. Projected relative accuracy 1% (Chudakov).



EPOLEGS4: Polarized e- thru Different Targets



•Looking for help of all types in all areas

• Need viable polarimetry for demonstration

• Proposal by Summer’s End (2002)

• Thoughts on Depolarization via ionization loss? (Multiple scatter does not look to be a problem)

• Is electron experiment useful?

• Is demonstration required?

What’s Going On?



Summary

•No Summary, Just Discussion.

nlc - the next linear collider project sheppard/pitthan july 14, 2015 power meeting june 8=9,2002...

Documents

linear collider project

linear collider project

llnl slide

sheppard slide

slac nlc vinod bharadwaj

slac nlc maria caturla

gev nlc primary electron

polarized positron production