Construction of a New Beamline at the SUNY Geneseo Pelletron

Accelerator for Calibrating a Thomson ParabolaMegan Crossman, Steven Hupcher, Charlie Freeman, Stephen Padalino: SUNY Geneseo

Christian Stoeckl: Laboratory For Laser Energetics

A new beamline with a general-purpose scattering chamber was constructed at theSUNY Geneseo 1.7 MV Pelletron accelerator laboratory. The beamline is equippedwith a general-purpose 28 inch scattering chamber which includes a targetmanipulator system, faraday cup, and a mounting for a surface barrier detector.

Sighting through steering magnet

Completed new line

Gafchromic (HD-810) Radiochromic film (RCF),normally used in medical dosimetry, was placed in thenew scattering chamber in an effort to create protondose calibrations.

Irradiated RCF with estimated angles of incidence

RCF upon immediate removal from scattering chamber

Incident Beam

SBDRCF

Faraday Cup

Au Foil

Schematic of RCF scattering experiment

Target Chamber Lid

Target Chamber

Gold Foil

SBD

Schematic of Thomson Parabola as it will be used for calibration on the new beamline at SUNY Geneseo

Abstract

New Beamline

Scattering Chamber

Thomson Parabola

Rutherford Scattering Experiment

Radiochromic Film

Motivation

The new beamline will be used for a wide variety of experiments:•Calibration of a Thomson Parabola•General Rutherford scattering•Calibration of radiochromic film•Experiments involving carbon ion beams•Experiments requiring the utilization of the large chamber

Future Plans

Twenty-eight inch scattering chamber

Target manipulator and surface barrier detector in chamber

Target manipulator with gold foils for Rutherford scattering

experiment

Magnetically coupled target manipulator

The new beamline will be used for experiments withRadiochromic and CR-39 film as well as experiments withcarbon ion beams. The Laboratory for Laser Energetics at theUniversity of Rochester hopes to use SUNY Geneseo’s datafrom the low energy proton Thomson Parabola calibrationsupon the installation of the Thomson Parabola atMultiterawatt Laser Facility.

Plot of the color density as a function of the inverse sin4(θ/2). Color density should be proportional to radiation dose so the plot should be

linear based on Rutherford’s scattering equation.

1911: Thomson’s brilliant idea: what happens if we use parallel electric and magnetic fields to deflect ions?The goal of the Thomson Parabola is to measure proton energies ~0.5 MeV to ~20 MeV with energy uncertainties of 10% or better.

x (magnetic)

• Deflection due to magnetic field ~q/p

• Deflection due to Electric field ~q/KE

• Ion traces form parabolic curves on detector plane

N

SElectric Deflection toward bottom of screen (y direction)

Magnetic Deflection into screen (x direction)

B

qx c

p 2E

qy c

KE

2

2

pKE

m

2

2

E

B

cmy x

q c

y (electric)

Note: cE and cB depend on electric and magnetic field strengths and geometry only

Possible applications include:•Fast Ignition•Medical Proton Therapy•Injector for traditional accelerators

Blow-offplasma

AcceleratedProtons and other ions

Laser Incidence

Planar Target

E ~ 1 TV/m

Thomson Parabola

Pinhole

NEC 1.5MV Tandem PelletronAccelerator (5SDH)

Aligning quadrupole magnets

Assembling the Thomson Parabola

The chamber of the Multiterawatt Laser

Use of Thomson Parabola on MTW for measuring high energy protons.

Accelerator prior to installation

The new line in operation

3D CAD drawing of the Thomson Parabola on MTW

Funded in part by the US Department of Energy through the Laboratory for Laser Energetics