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Low Energy Electron Beam Goal of This Presentation Review a R&D case study of low energy electrons Dosimetry issues associated with low energy electrons Evaluation of dose measurements SUBGROUP NAME: REGION AND/OR PROJRCT |

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Low Energy Electron Beam

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

Confidential | 3

Goal of This Presentation

Review a R&D case study of low energy electrons
Dosimetry issues associated with low energy electrons
Evaluation of dose measurements

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Scenario

The Ask: Dosimetry for absorbed dose measurements for a low energy electron beam irradiation of a thin product Dose map to evaluate single and double sided processing Process Optimization: Energy, Air Gap

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Preliminary Evaluation

Preliminary evaluation consisted of Monte Carlo modeling:

a. Air gap
b. Energy
c. Dose depth profile for dosimetry assessments
d. Dose delivery as a double sided process simulated as

the summation of two single sided irradiations

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Air Gap Models

In low energy electron beam applications energy losses are heavily influenced by the air gap; energy losses in air Two energy models were constructed to evaluate the energy losses at several air gaps Initial Energy Air Gap 240 keV 10mm 15mm 20mm 25mm 300 keV 10mm 15mm 20mm 25mm

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Air Gap Models

Initial Energy Air Gap 240 keV 10mm 15mm 20mm 25mm 220.4 keV 219.2 keV 217.8 keV 215.8 kEv 300 keV 10mm 15mm 20mm 25mm 290.2 keV 289.1 keV 287.4 keV 286.3 keV

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Air Gap Models

Conclusions:

a. As the air gap is increased a corresponding increase in

the energy loss over the air gap occurs

b. Energy losses were larger for lower initial energy

primarily due to energy loss in window

c. Air gap variation due to product conveyance was

known to be ±5mm ; a 15mm air gap was selected

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Energy

Dose depth profiles were modeled to provide insight:

a. Expected penetration of the thin product
b. Estimate dose gradients for dosimetry assessment
c. Three energies were initially evaluated

220 keV 250 keV 275 keV

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Dose Depth Profiles

‐1E‐12 1E‐12 2E‐12 3E‐12 4E‐12 5E‐12 6E‐12 50 100 150 200 250 300 350 Relative Dose μm

Monte Carlo Simulation 15mm air gap in 1.12 g/cm3 absorber

220 keV 250 keV 275 keV

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Dose Depth Profiles

Conclusions:

a. Higher energies provided larger penetration
b. Higher energies provided smaller dose gradients*

*smaller dose gradients were a consideration for dosimetry

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Dose Depth Profiles

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Dosimetry

The thinner the dosimeter the smaller the dose gradient Significant when determining the absorbed dose measurement with dosimetry, i.e. average dose vs. apparent dose Large dose gradients over the thickness of the dosimeter would cause differences between average dose and apparent dose

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Dose Depth Profiles

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Dosimetry

Dose gradients over 18 um increments were evaluated using dose depth profiles A low energy provided the most significant challenge with respect to dose gradients

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Dosimetry

The 220 keV dose depth profile data was used to estimate the residuals of the actual dose depth profile and the estimate assuming constant gradient slope through the 18 um thickness of the B3 dosimeter

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Dosimetry

0.99 1 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 5 10 15 20

220 keV 0 to 18 um

1.07 1.08 1.09 1.1 1.11 1.12 1.13 5 10 15 20

220 keV 19 to 36 um

total res 0.002 0‐9 0.000365 10‐18 0.002554 total res 2E‐07 0‐9 0.00057 10‐18 0.000713

1.12 1.13 1.14 1.15 5 10 15 20

220 keV 37 to 54 um

total res 7E‐07 0‐9 0.000719 10‐18 0.000757

1.12 1.13 1.13 1.14 1.14 1.15 5 10 15 20

220 keV 55 to 72 um

total res ‐1.9E‐06 0‐9 0.000759 10‐18 0.000719

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Dosimetry

a b c d e f g h i j k 0.000 0.100 0.200 0.300 0.400 0.500 0.600 0.700 0.800 0.900 1.000 1.100 1.200 1.300 1.400 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250

Dose Depth 220keV

segment sum res. 1‐9 10‐18 a 2.000E‐03 0.000365 0.002554 b 2.000E‐07 0.000570 0.000713 c 7.000E‐07 0.000719 0.000757 d ‐1.900E‐06 0.000759 0.000719 e 5.000E‐07 0.000720 ‐0.000719 f 8.000E‐07 0.000681 ‐0.000680 g 0.000E+00 0.000833 ‐0.000833 h 1.600E‐06 0.001256 ‐0.001255 i ‐1.000E‐07 0.001388 ‐0.001388 j 7.000E‐07 ‐0.000375 0.000375 k 2.000E‐07 ‐0.002309 0.002309

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Dosimetry

No significant difference: apparent dose vs. average dose

1.12 1.125 1.13 1.135 1.14 1.145 5 10 15 20

220 keV 55 to 72 um

1.12 1.125 1.13 1.135 1.14 1.145 5 10 15 20

Uniform vs. Gradient 220 keV 'd'

total res ‐1.9E‐06

0.000002

1.132 = 0.00017%

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Dosimetry

Calibration irradiation of the B3 can be done either with low energy or high energy (in‐situ) If low, Alanine film would need to be corrected (apparent dose ≠ average dose) If high, Alanine film apparent dose = average dose B3 in either low or high, apparent dose = average dose

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Dose Mapping Simulations

Dose mapping simulations using Monte Carlo Simulate 2‐sided irradiation with sum of 2 single‐sided models

location 18 28 48 58 88 98 118 128 148 158 178 188 208 218 238 248

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Dose Mapping Simulations

Dose mapping simulations using Monte Carlo

0.00E+00 2.00E‐06 4.00E‐06 6.00E‐06 8.00E‐06 1.00E‐05 1.20E‐05 1.40E‐05 1.60E‐05 50 100 150 200 250 300 1st pass 2nd pass 1‐2 pass

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Dose Mapping Simulations

Dose Map vs. Monte Carlo 240 keV

Model Prediction Dose Map Data

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SUBGROUP NAME: REGION AND/OR PROJRCT | Confidential | Month 00, 0000

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Low Energy Electron Beam

Conclusions:

a. Low energy electron beam was viable for thin product

processing

b. At energies of 220 keV the difference of average dose

and apparent dose are negligible in an 18 um thick dosimeter that is optically assayed

c. Execution of dose mapping proves a challenge as

Low Energy Electron Beam

Goal of This Presentation

Scenario

The Ask: Dosimetry for absorbed dose measurements for a low energy electron beam irradiation of a thin product Dose map to evaluate single and double sided processing Process Optimization: Energy, Air Gap

Preliminary Evaluation

Preliminary evaluation consisted of Monte Carlo modeling:

the summation of two single sided irradiations

Air Gap Models

In low energy electron beam applications energy losses are heavily influenced by the air gap; energy losses in air Two energy models were constructed to evaluate the energy losses at several air gaps Initial Energy Air Gap 240 keV 10mm 15mm 20mm 25mm 300 keV 10mm 15mm 20mm 25mm

Air Gap Models

Initial Energy Air Gap 240 keV 10mm 15mm 20mm 25mm 220.4 keV 219.2 keV 217.8 keV 215.8 kEv 300 keV 10mm 15mm 20mm 25mm 290.2 keV 289.1 keV 287.4 keV 286.3 keV

Air Gap Models

Conclusions:

the energy loss over the air gap occurs

primarily due to energy loss in window

known to be ±5mm ; a 15mm air gap was selected

Energy

Dose depth profiles were modeled to provide insight:

220 keV 250 keV 275 keV

Dose Depth Profiles

Dose Depth Profiles

Conclusions:

*smaller dose gradients were a consideration for dosimetry

Dose Depth Profiles

Dosimetry

The thinner the dosimeter the smaller the dose gradient Significant when determining the absorbed dose measurement with dosimetry, i.e. average dose vs. apparent dose Large dose gradients over the thickness of the dosimeter would cause differences between average dose and apparent dose

Dose Depth Profiles

Dosimetry

Dosimetry

The 220 keV dose depth profile data was used to estimate the residuals of the actual dose depth profile and the estimate assuming constant gradient slope through the 18 um thickness of the B3 dosimeter

Dosimetry

Dosimetry

Dosimetry

No significant difference: apparent dose vs. average dose

Dosimetry

Calibration irradiation of the B3 can be done either with low energy or high energy (in‐situ) If low, Alanine film would need to be corrected (apparent dose ≠ average dose) If high, Alanine film apparent dose = average dose B3 in either low or high, apparent dose = average dose

Dose Mapping Simulations

Dose mapping simulations using Monte Carlo Simulate 2‐sided irradiation with sum of 2 single‐sided models

Dose Mapping Simulations

Dose mapping simulations using Monte Carlo

Dose Mapping Simulations

Dose Map vs. Monte Carlo 240 keV

Low Energy Electron Beam

Conclusions:

processing

and apparent dose are negligible in an 18 um thick dosimeter that is optically assayed

physical placement of a dosimeter influences the absorbed dose measurement