High-Energy_Proton_Testing_SOW.pdf

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Statement of Work (SOW) High-Energy Proton Radiation Effects Testing of

Microelectronic and Photonic Components and Systems

General Information Scope This SOW addresses the usage of facilities required for high kinetic energy (≥ 125 MeV) proton accelerator facilities to support the characterization and evaluation of radiation effects in microelectronic and photonic components and systems. Requirements span dosimetry, beam kinematics, upper and lower irradiation area limits, upper and lower target exposure time limits, beam movement and delivery methods, beam temporal structure, and general radiation safety considerations.

NASA (National Aeronautics and Space Administration) intends to use the vendor’s facilities for NASA employee and contractor access.

Background Particle accelerators are used to evaluate risk and qualify electrical, electronic, electromechanical, and electro-optical (EEEE) components and systems for use in the space environment. In particular, protons simulate solar particle events, such as coronal mass ejections, and protons trapped in planetary magnetic fields. These radiation fields contribute to a range of effects, including total ionizing dose (TID), total non-ionizing dose (TNID), and single-event effects (SEE), all of which can negatively impact the reliability and availability of aerospace systems.

TID and TNID represent long-term cumulative degradation leading to parametric and/or functional failure. SEE generate soft or hard errors caused by protons and heavy ions (atomic number > 1) depositing energy as they transit materials. For high-energy protons, SEE are caused by indirect ionization via recoiling nuclei generated from 𝑝 + 𝑋 nuclear interactions.

Typical NASA radiation facility users are responsible for the production and/or oversight of space flight electronic systems. They perform qualification tests on discrete EEEE components and integrated circuits. They also perform system validation tests and risk assessments on assembled hardware (e.g.

circuit boards and electronics boxes). Additionally, NASA users lead semiconductor research that examines new technology sensitivity to space radiation in advance of flight use or to evaluate radiation hardening techniques. Finally, NASA carries out radiation testing to develop and define qualification

(test) methods.

In October 2014, the aerospace and semiconductor industries lost approximately 2000 yearly-hours of high-energy proton beam time when the Indiana University Cyclotron Facility closed. Deprived of a single, consistent source of high-energy protons, NASA must fill this need by engaging a wider range of proton accelerator facilities, such as those that primarily exist to serve the medical radiation therapy community.

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Objective By engaging a diverse pool of test facilities able to provide suitable high-energy protons, NASA can gather radiation effects data to evaluate risk and qualify EEEE components and systems for its missions while meeting program and project schedules in a cost-effective and efficient manner.

Technical Requirements General Table 1 outlines sample considerations for proton testing of EEEE components and systems. These considerations are unique for each individual test facility and have bearing on how radiation testing is conducted.

Table 1: Considerations for Proton Testing

Particle Practical

Dosimetry and particle detectors Setup cable lengths Beam uniformity Device under test thermal management Energy mapping to the relevant space environment Speed / performance of device under test Particle localization Test conditions Stray / secondary particles such as neutrons Power Particle range Mechanical Flux rates and stability Staging area Beam structure (pseudo-continuous or spills) Shipping / receiving Activated material storage

Operator model (who runs the beam)

Table 2 outlines major differences between patient treatment and electronics proton exposure. These differences may require different accelerator operation modes or dosimetry data reduction methods to account for space user needs.

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Table 2: Patient vs. Electronics Proton Exposure

Patient Electronics (Typical)

Measurement: dose in tissue/water Measurement: dose (material – Si, SiO2, GaAs, etc.)

and particle rates (fluence – protons/cm2 and flux – protons/cm2/s)

Beam penetration: use Bragg peak to stop the beam in the patient

Beam penetration: beam goes through the target with a beam stop behind the target

Exposure stop: cumulative dose Exposure stop: cumulative dose, fluence, number of recorded events, degradation, or an unanticipated event / failure. When an unanticipated event occurs, the beam stop may be manual, automatic, or via verbal command such as “stop”. Coordinating “beam on” with device under test operation is important as well.

Target size: tumor Target size: single device / chip (1 cm x 1 cm) to a full assembly (20 cm x 20 cm or larger)

Beam delivery: pencil beam, wobble, uniform scan, or fixed point/scatter

Beam delivery: prefer fixed point / scatter

Beam timing structure: less important Beam timing structure: when particle arrives versus electronics operation can be important, but not always

Patient exposure: a few minutes Target exposure: flexible, seconds to minutes, depending on stop criteria. There are often many exposures (test runs) per target (10s to 100s)

Beam movement: gantry or fixed Beam movement: fixed

Setup The items noted below are required for NASA testing at a vendor facility.

NASA special characteristic requirements shall include the following. In instances where these requirements cannot be met, the vendor shall provide mitigating rationale to justify facility use.

1. Reasonable access to the test stand and/or data acquisition areas during the afternoon/evening of the day before the scheduled irradiation activities (i.e., this is set up time and does not include any proton beam time).

a. Reasonable access can be negotiated on a per test basis depending on facility constraints, but needs to permit a 2-hour minimum for unpacking and setup time to facilitate efficient use of subsequent proton beam time.

2. Data acquisition and test stand areas – test stand details covered below.

3. An entrance / path to the data acquisition and test stand areas, separate from and/or non-interfering with any other activities and procedures.

4. Parking spaces for visiting test personnel near the entrance to the test facility.

a. If long-term parking spaces are located away from the test facility, access to a loading dock in proximity to the test area is a suitable substitute.

5. Access to restrooms and water fountains at all times.

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6. A separate / designated area adequate for loading / unloading and packing / unpacking supplies.

7. A secure area for storing test articles / test support equipment, before and after the test.

8. Test data acquisition / control / user area with adequate lighting, space for at least two 4 ft x 8 ft tables, and several independent (i.e., separately fused) 110 V power outlets.

a. In ideal circumstances, the test data acquisition/control area will be co-located with the beam control station. Typical radiation tests require seating and computer space for 3-4 users in addition to test control equipment.

9. Adequate shielding, monitoring and safety interlocks to keep personnel radiation exposure as low as reasonably achievable (ALARA) and consistent with prevailing regulations and administrative controls.

10. Individual personnel dosimetry (e.g., active and/or passive) issued to each guest user. The dosimeter will stay at the facility when user(s) depart the facility each day. The facility will collect these dosimeters at the end of the test campaign and report absorbed dose to users consistent with prevailing regulations and administrative controls.

11. Assistance with returning test articles / test support equipment (e.g., calling shipper (e.g., FedEX, UPS, etc.)) to collect shipping crates and/or packages once they are deemed safe to be transported.

The vendor shall provide a test stand area (i.e., area inside irradiation vault / shielded room) that includes the following. In instances where these requirements cannot be met, the vendor shall provide mitigating rationale to justify facility use.

1. Safe access at all times when users are scheduled to work at / access the facility.

2. Radiation exposures performed in air.

3. Computer control of beam dosimetry.

4. Ability to manually place or automatically control a beam stop.

5. Shielding materials to reduce primary and/or secondary radiation fields (e.g., high-density polyethylene blocks, lead bricks, powered borax soap, etc.) for the purpose of protecting user test devices and/or equipment.

a. If a facility does not have suitable user-available shielding materials, notify NASA and these materials can be shipped directly to the facility.

6. Beam collimating system to control final beam size at a test location.

7. An accurate beam energy and uniformity measurement system.

8. A stable mounting table and/or fixturing structure suitable for clamping / holding a device under test. The mounting table and/or fixturing structure does not necessarily have to be motorized or remote controlled in the x, y, and/or z-dimensions, but it needs to be able to safely support reasonable device under test hardware and associated cabling.

9. Adequate lighting, space for at least one 4 ft. x 8 ft. table, and several independent (i.e., separately fused) 110 V power outlets.

10. Reasonable (i.e., unimpeded) cable run access from the test data acquisition / control / user area to the test stand area in the vault. This path can include dedicated cable trays / pipes, gaps under doors, etc.

a. The facility shall make a best effort to measure and report the cable run length between the test stand area and the designated test data acquisition / control / user area.

Alterations to the path between these two locations (e.g., doors that have less / no floor

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Nominal Proton Beam Characteristics The vendor shall provide the following. In instances where these requirements cannot be met, the vendor shall provide mitigating rationale to justify facility use.

1. Variable monoenergetic protons with kinetic energies from 125 MeV to 200 MeV. Kinetic energies in excess of 200 MeV are acceptable.

2. Variable proton fluxes between 1x107/cm2/s and 1x109/cm2/s. Vairable flux ranges outside of this window will be considered.

3. Individual test run fluences up to 1x1011/cm2, with single exposure durations routinely exceeding 10 s.

4. Irradiation area from 1 cm2 up to 15 cm x 15 cm – spot size will be variable.

5. Less than 20% variance on beam uniformity over collimated beam area.

a. < 10% variance preferred

6. Beam structure:

a. Cyclotrons are preferred (random particle delivery as a function of time). Pulsed beam structures from a synchrotron are acceptable for many, but not all, applications.

b. Fixed spot or scatter beams are preferred (random particle delivery over target area).

Scanning beams may be acceptable, but need to consider device or system under test versus timing of beam spots.

7. Absolute dosimetry exceeding (better than) 10% routinely.

Beam Time Billing, Beam Use Log, and Purchased Beam Time Expiration The vendor shall permit and bill a minimum of four hours for facility use per test campaign. Time blocks less than this are neither practical nor efficient. NASA prefers a minimum of 8-hour blocks of beam time and can adjust to fill available time so long as it does not drop below the 4-hour minimum.

The vendor shall provide and keep a log that tracks NASA beam time purchased, beam time used, and unused beam time purchased (i.e., beam time credit hours). NASA will use purchased beam time within one year of funding obligation under an agreement call; hours will be forfeited otherwise. NASA’s goal is to use all funding available under each individual call to avoid buildup of uncosted obligations resulting from facility underutilization and/or unexpected test campaign cancellation.

Facility Scheduling Individual test schedules shall be delineated for each call under this agreement. Test facility locations may be determined by the proximity of the facility to the NASA Center’s end users and/or their ability test campaign schedule requirements.

Data and Deliverables The vendor shall provide the following information on the schedule indicated.

1. Within one week of a completed test campaign, a summary of dosimetry data from individual radiation test runs.

a. Exposure dosimetry information shall be provided as follows:

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i. Average exposure flux (#/cm2/s),

ii. Fluence (#/cm2), and

iii. Absorbed dose (Gy(Si)).

2. Quarterly, a status report of beam hours used and beam hours remaining.

Applicable Documents See associated document addressing relevant dosimetry conversions.

Security Requirements All work associated with this SOW is unclassified; no security clearances are required.

Appendix Supplemental Definitions Total Ionizing Dose (TID)

Energy deposited per unit mass of material as a result of ionization

NOTE: The SI unit for absorbed dose is the gray (1 Gy = 1 joule/kg). However, the deprecated CGS unit rad (radiation absorbed dose) is still used frequently (1 rad = 100 ergs/g = 1 cGy). It needs to be defined as a function of the target material, e.g. Gy(Si) or rad(Si) for TID in silicon.

Total Non-Ionizing Dose (TNID), or Non-Ionizing Energy Loss (NIEL) dose

Energy absorption per unit mass of material which results in damage to the lattice structure of solids through displacement of atoms

NOTE: Although the SI unit of TNID or NIEL dose is the gray (1 Gy = 1 joule/kg), for space radiation effects MeV/g(material) is more commonly used in order to avoid confusion with ionizing energy deposition, e.g. MeV/g(Si) for TNID in silicon.

Single-Event Effects (SEE)

An effect caused either by direct ionization from a single traversing particle or by recoiling nuclei emitted from a nuclear interaction initiated by a single traversing particle. These effects can be either destructive or non-destructive. SEE is a term that covers a wide range of more specific sub-categories of effects.

List of Attachments

Attachment A: Radiation Effects Dosimetry at Proton Therapy Facilities