Dr. Andy HollermanDr. and Mrs. Sammie W. Cosper/BORSF Endowed

Associate Professor of PhysicsAssociate Director, Louisiana Accelerator Center

University of Louisiana at LafayetteLafayette, Louisiana 70504hollerman@louisiana.edu

Louisiana Accelerator Center

Spring 2013

Agenda

• Overview and History• Facilities• LAC Research Examples

– Micromachining– Solar Sails– Half Brightness Fluence

• Conclusions• Contact Information

Overview and History

OverviewThe Louisiana Accelerator Center (LAC) at the University of Louisiana at Lafayette (UL Lafayette) is recognized as a Research Center by the Louisiana Board of Regents (BOR) with active programs emphasizing materials analysis, microfabrication and high energy focused ion beam physics.

Location

• LAC (A on map) is located at 320 Cajundome Boulevard and is across the street from the Cajundome and Cajun Field in Lafayette, Louisiana.

• It can be accessed by auto from Reinhardt drive.

Early History• LAC had its beginnings in the mid 1970’s when the University of Southwestern

Louisiana (USL, now UL Lafayette) made two surplus property acquisitions:- The first acquisition, a High Voltage engineering Corporation Model KN 3 MV

Van de Graaff accelerator system valued at about one million dollars, was obtained from the NASA's Johnson Space Flight Center in Houston, Texas.

- The second acquisition, the complete contents of a machine shop and a metrology shop, were acquired from NASA's Michoud fabrication facility in New Orleans.

- The moving costs for bringing this equipment to campus was minimal because it was accomplished by physics faculty and staff.

• In 1976, a 4,000 ft2 bare metal building was constructed on Reinhardt Drive, then Souvenir Gate, on a piece of university property used to graze cattle.

• The KN accelerator was installed and made operational for low energy protons and a shop established using the Michoud equipment and additional equipment provided by the offices of the Quality Machine and Pipe Company, currently the Quality Machine Shop, Incorporated.

• In 1981 a shielded accelerator building was constructed at a cost of $680,000 and joined with the existing metal structure.

Later History• The KN accelerator was moved into the shielded structure and the machine shop

moved into the accelerator's former location. • A High Voltage Engineering Corporation Model JN 1 MV Van de Graaff accelerator

system was obtained in 1982 from the University of Virginia, installed in the target room and used as an instructional tool for students.

• In 1985, with the initiation of the Louisiana Quality Support Fund (LEQSF), a plan was developed by the research staff to establish a complete ion beam research facility.

• By 1990, two LEQSF grants were obtained to acquire a high-energy accelerator and an analysis chamber with associated detectors.

• This new accelerator was installed in the site originally occupied by the KN accelerator, which was sold at auction in November 2000.

• In 1997, an ion microprobe system was funded by LEQSF and became operational in 2001.

• In 2003, funding was obtained to acquire an additional set of triplet lenses and a JEOL 6460LV scanning electron microscope to be added to the present microprobe system for the development of a unique (patented) sextuplet focusing system for high-energy ions.

• Since 1990, funding at LAC for ion beam research and related equipment has exceeded $6.3 million.

Sources of Ionizing Radiation

• Natural:- Background radioactive materials on Earth- Space radiation from all non-Earth sources

• Anthropogenic:- Medical applications- Industrial applications- Radioactive contamination (includes

atmospheric testing and accidents)Facilities

LAC Vault Diagram

LAC Pelletron Accelerator

1.7 MV 5SDH-2 Tandem Pelletron AcceleratorNational Electrostatics Corporation

Pelletron Charging System

LAC Negative Ion Sources

RF Charge ExchangeSource

Source of Negative Ions by Cesium Sputtering (SNICS II)

DuoplasmatronPicture of the LAC Sourcea

LAC BeamsSource Available Beams

RF Protons and alpha particles

SNICS IIProtons and elements from solid

sputter cathodes like Li, B, C, F, N, O, Ti, Ni, Cr, Co, Zn, Mo, Al, Eu, and Au.

Duoplasmatron Protons

LAC Beamlines

Analysis

HEFIB

Implant

Beamline Images

High Energy Implant andAnalysis Chamber

High Energy Analysis Chamber

1.7 MV 5SDH-2 Pelletron

Proton Beam Spot

HEFIB SystemMounted Samples

Samples and Measurements

PIXE/RBS Chamber at theLouisiana Accelerator Center

Mounted Samples inPIXE/RBS Chamber

ZnS:Mn TL Excitedby 3 MeV Protons

Irradiated Spots ShowingProton Damage

ZnS:Mn in PPMS Paint PPMS Paint(Proton Dose ~ 1015 mm-2)

UVLight

LAC CapabilitiesTechnique Type

(A/M)*Energy (MeV) Particle Current Beam

Size Application

Rutherford Backscattering Spectrometry (RBS) A 1 - 3 He < 100 nA ~1 mm Elemental and thin film analysis

Channeling (RBS) A 1 - 3 He < 50 nA ~1 mm Structure analysis and light element detection in crystals

Micro-RBS A 1 - 3 He < 1 nA 1 - 100 µm Position sensitive elemental analysis

Particle InducedX-Ray Emission (PIXE) A 1 - 3 H < 1 µA ~1 mm Trace elemental analysis

In-Air PIXE A 1 - 3 H < 1 µA 1 - 5 mm Trace elemental analysis

Micro-PIXE A 1 - 3 H < 500 pA 1 - 100 µm Position sensitive trace elemental analysis

Scanning Transmission Ion Microscopy (STIM) A 1 - 3 H & He < 1 nA 1 - 100 µm Analyze structure of thin

samples using transmitted ions

Nuclear Reaction Analysis (NRA) A Variable Variable

ions 1 - 10 µA 1 – 3 mm Enhanced sensitivity to selected elements

Ion Research Implantation and Irradiation M 1 - 10 All ion

beams Variable 5 - 20 mmMaterial modification, device development, and damage

studies

Micromachining M 1 - 3 H < 1 nA 1 - 50 µm Machining small complex shapes using a scanned beam (no mask)

* A = Analysis M = Modification

Analysis Accuracy and Sensitivity

Analysis Technique Acronym Detected

Elements Sensitivity Accuracy

Rutherford Backscattering Spectrometry

RBS Be to U Bulk: 10-4

Surface: 1 to 10-4Composition: < 1%

Layer Thickness: 5%

ParticleInduced X-ray

EmissionPIXE Na to U 10-6 (ppm) 10%

Nuclear Reaction Analysis NRA H to Al 10-2 to 10-6 10%

Other Capabilities• The HEFIB beam line is equipped with a liquid nitrogen-cooled standard x-ray detector

(Princeton Gamma Tech), and a Peltier-cooled Bruker Quantax EDS detector:– The HEFIB system can produce a 1 x 1 µm beam with high-resolution images of tested

materials.• Recently, the center implantation beam line was modified to allow analysis of biological

materials or other delicate samples in ambient conditions using techniques such as in-air PIXE:– A thin titanium window was added to the output port of the implantation chamber allowing

for the beam to be brought out into the air.• The accelerator vault further contains a bench with appropriate optical and digital microscopes

as well as a JEOL model 6460LV scanning electron microscope.• A small library and computer access area is also located in a separate room adjacent to the

accelerator control station.• A metal vapor deposition chamber, small Carver press, and a fully equipped machine shop are

also located in the metal support building.• The shop contains several metal saws, a micro-lathe, an industrial-sized lathe, a mill, and

several pieces of welding equipment.• The shop is also fairly well equipped for electronics work (soldering, testing, and assembly of

prototypes). • A separate chemistry lab houses a fume hood, spin-coater (for analyses of e.g., powdered

material or suspensions), a micro-saw for cutting of crystals and ceramics, a sputter coater and related items, plus two high temperature ovens and a heated incubator.

• In addition, most regular wet-lab items (pipettes, chemicals, glassware, refrigerator etc.) are also available.

LAC Research Examples

LAC Microlithography and Micromachining

µPIXE Solar Sail Analyais

Aluminum Kα Sulfur Kα

Phosphorus Kα Silicon Kα

• 1,000 x 1,000 µm microprobe PIXE scans of a Mylar solar sail material provided by MSFC.

• Analysis completed at LAC using a 2 MeV proton beam with a current of less than 100 pA.

• These scans show Kα x-rays from aluminum, sulfur, phosphorus, and silicon.

• Scan regions that are black correspond to high x-ray yield.

• Areas that are white correspond to no x-ray yield.

• Shades of gray correspond to intermediate yield values.

• Data clearly shows the outline of a bundle of Kevlar threads (500 µm thick) that is glued to the back of the aluminized Mylar sail material.

• This analysis appears to show the glue used to attach the Kevlar fiber bundles to the aluminized Mylar sail material contained sulfur, phosphorus, and silicon.

• W.A Hollerman, T.L. Stanaland, D. Edwards, P. Boudreaux, L. Elberson, J. Fontenot, E. Gates, R. Greco, M. McBride, and A. Woodward, Accelerator-Based PIXE and STIM Analysis of Candidate Solar Sail Materials, 17th International Conference on the Application of Accelerators in Research & Industry, Edited by J.L. Duggan and I.L. Morgan, American Institute of Physics, 452-455 (2003).

STIM Solar Sail Analyais

• 1,000 x 1,000 µm microprobe STIM scans of a Mylar solar sail material provided by MSFC.• Analysis completed at LAC using a 2 MeV proton beam with a current of less than 100 pA.• Regions in each scan that are black correspond to large numbers of detected scattered protons. • Areas that are white in the scan correspond to no detected particles.• Shades of gray correspond to intermediate quantities of detected protons.• The numbers on top of each image correspond to the STIM scan number as displayed by the data

acquisition computer.• This analysis appears to show the Kevlar bundle is cylindrical in shape.• W.A Hollerman, T.L. Stanaland, D. Edwards, P. Boudreaux, L. Elberson, J. Fontenot, E. Gates, R.

Greco, M. McBride, and A. Woodward, Accelerator-Based PIXE and STIM Analysis of Candidate Solar Sail Materials, 17th International Conference on the Application of Accelerators in Research & Industry, Edited by J.L. Duggan and I.L. Morgan, American Institute of Physics, 452-455 (2003).

Data Acquisition System

• LabVIEW graphical environment• Written in the G programming language• Acquisition and data analysis software• Two analog inputs to computer

• Calculated half brightness dose (N1/2)• Variable beam irradiation area• Time increment (Δt) = 1.0 s• Radiation Source = 3 MeV protons

3 MeV Proton DataPhosphorPhosphor Crystal

FormCited

Reference3 MeV Proton N1/2

(x 1014 mm-2)Material DopantCrystalForm

CitedReference

3 MeV Proton N1/2

(x 1014 mm-2)

YAG Ce

PPMS Paint W.A. Hollerman et al., IEEE Transactions of Nuclear Science,

vol. 50 (4), pp. 754-757 (2003).

1.28 ± 0.21

YAG CeSingle Crystal

W.A. Hollerman et al., IEEE Transactions of Nuclear Science,

vol. 50 (4), pp. 754-757 (2003). 4.03 ± 0.65YAG Ce

Pressed Cellulose

Tablet

W.A. Hollerman et al., IEEE Transactions on Nuclear Science, vol. 51 (3), pp. 1080-1083 (2004).

0.11 ± 0.01

Y2O2S Eu PPMS Paint W.A. Hollerman et al., Materials Research Society Symposium,

vol. 560, pp. 335-340 (1999).

0.60 ± 0.46

Gd2O2SPr

PPMS Paint

W.A. Hollerman et al., Materials Research Society Symposium,

vol. 560, pp. 335-340 (1999).0.16 ± 0.11

Gd2O2STb

PPMS Paint

W.A. Hollerman et al., Materials Research Society Symposium,

vol. 560, pp. 335-340 (1999).0.20 ± 0.13

Y2SiO5 Ce Single CrystalW.A. Hollerman et al., IEEE

Transactions of Nuclear Science, vol. 40 (5), pp. 1355-1358 (1993).

0.28 ± 0.01

Tb3Ga5O12 None Single CrystalW.A. Hollerman et al., Journal of Materials Research, vol. 10 (8),

pp. 1861-1863 (1995).0.12 ± 0.01

ZnS Mn PPMS PaintW.A. Hollerman et al., IEEE

Transactions of Nuclear Science, vol. 51 (4), pp. 1737-1741 (2004).

0.92 ± 0.07

Polysiloxane paint with polycrystalline phosphor grainsSingle slice of the given phosphor crystal

PPMS PaintSingle Crystal

--

PbPO4:Eu Glass Spectra(6 wt.% Eu Sample)

Intensity grows with 3 MeV fluence.

ZnS:Mn Decay Time ResultsA

B

C

D

3 MeV protons

Annealing Effects(3 MeV Protons on ZnS:Mn Paint)

• A comparison of the temperature versus decay time curves indicates that proton irradiation changes the temperature sensitivity of ZnS:Mn.

• As the curve for the irradiated sample approaches the unirradiated sample, the values begin to follow the unirradiated curve.

• There appears to be annealing of the irradiation damage from the ZnS:Mn.

Fluence = 2.28 x 1013 mm-2 Fluence = 7.39 x 1013 mm-2

Y2O2S:Eu and PPMS Paint µPIXE Scan

• PPMS paint sprayed on a glass slide

• 2 MeV proton beam• 2 x 2 µm beam area• Y, S, and Eu - phosphor• Si and Ca - slide• 100 x 100 µm scan• Taken at LAC nuclear

microprobe

Y S Eu

Ca

20 µm

Si

(opposite color image)

Y2O2S:Eu and PPMS Paint µPIXE Scan

Y S Eu

Ca

10 µm

Si • PPMS paint sprayed on a glass slide

• 2 MeV proton beam• 2 x 2 µm beam area• Y, S, and Eu - phosphor• Si and Ca - slide• 50 x 50 µm scan• Taken at the LAC nuclear

microprobe

Y3(Al,Ga)5O12:Ce and PPMS µPIXE Scan

• PPMS paint sprayed on an aluminum slide

• 2 MeV proton beam• 2 x 2 µm beam area• Y, Ga, and Ce - fluor• Si - PPMS • Al - Slide and fluor• 50 x 50 µm scan• Taken with the LAC nuclear

microprobe

Y Ga Ce

AlSi

(opposite color image)10 µm

Conclusions• LAC is a BOR certified Research Center at UL

Lafayette committed to assisting NASA with its research and development mission.• LAC got started with equipment donations from

NASA in the 1970s.• LAC is participating in the NASA-EPSCOR state of

Louisiana proposal to measure the effects of radiation on the structure of DNA.• Thank you for your attention.

Contact Information• Website: http://lac.louisiana.edu

• Interim Director: Dr. Karl Hasenstein (hasenstein@louisiana.edu)

• Associate Director: Dr. Andy Hollerman (hollerman@louisiana.edu)

• Operations Manager: Nick Pastore (nick@louisiana.edu)