Mike JenkinsLancaster University and The Cockcroft

Institute

Presentation OverviewPositron source requirements of future

collidersUndulator based positron source designCurrent undulator developmentsUpdate on Target material measurements

06/04/2011 IOP NPPD Glasgow 2

Requirements of a Positron SourceThere are currently three proposed designs for particle accelerators which require a positron production rate of >1014 e+/s

Conventional solutions to produce positrons have a production limit of 6 x 1012 e+ /s

Collider Positron Production Rate (number of e+ /s)

ILC 3.9 x 1014

CLiC 1.1 x 1014

LHeC 3.1 x 1015

Future Positron Source DesignsCurrent proposed designs for the positron source at future colliders include:

laser-Compton based source

Undulator based

Hybrid Target (crystalline target and amorphous target)

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Undulator Based Positron Source

Schematic of ILC RDR Positron Source

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Length of Undulator

Number of γ / e-

Heat Load on Target

Number of e+ /e-

~150m to 250m 200 ~20 kW (beam)Up to 20 kW (eddy currents)

2

Undulator DevelopmentsCurrently the

superconducting undulator planned for use in the positron source is made using NbTi conductors

NbTi undulator prototype for ILC is currently being tested at RAL

Simulations into different superconductors are on going, the work presented here is based on Nb3Sn conductors

Parameter

Design Value

Test Results

Period 11.5 mm 11.6 mm

Field on Axis

0.86 T 0.88 T

Undulator Developments OP

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A 3

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latio

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Flux Density: 0.070 T to 4.85 T

Undulator Developments

06/04/2011 IOP NPPD Glasgow 8

Positron Source Target

Courtesy of Ken Davies, Daresbury Lab

Courtesy of Jim Rochford, RAL

0.5 to 1.5 T Dipole Magnet

1 m Titanium Target

Eddy Current ResultsPeak Torque(Carmen)

Average Torque(Carmen)

Min Torque(Carmen)

Preliminary Data

Results for peak field of 0.5 T and target immersion depth of 30.25 mm

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Target Material ConductivityTo resolve the difference between simulations and the data the properties of the titanium are being investigated.

Currently the electrical and thermal conductivity of the titanium is being measured

Expected Resistance

8.8 x 10-5 Ω

Expected Electrical Conductivity

5.62 x 105 S m-1

Expected Thermal Conductivity

6.70 W K-1 m-1

Target Material Conductivity

Samples

Probe 2

Probe 1

Sample Length (mm)

Width (mm)

Height (mm)

A 49.96 16.46 4.94

B 49.97 16.45 9.96

C 49.82 16.37 14.9206/04/2011 IOP NPPD Glasgow 12

Target Material Conductivity

Oxygen Free Copper Contacts

Springs

Sample06/04/2011 IOP NPPD Glasgow 13

Target Material ConductivityExperimental setup

consists of a AC current source and nanovoltmeter connected to LabView

Only preliminary DC measurements taken so far

Trying to understand systematic effects causing shifts in the signal between consecutive data taking periods

SummaryUndulator simulations are promising, it

appears that the new wire could allow the undulator period to reduce from 11.5 mm to 10.0 mm keeping K constant

Awaiting confirmation about the performance of the Nb3Sn wire, current uncertainty about the performance of the wire at low field strength

Conductivity measurements of the target material are preliminary and there are a few issues still to resolve

06/04/2011 IOP NPPD Glasgow 15

Thank you for listening, are there any questions