Attachment_A_-_NIST_Statement_of_Work_(SOW).docx

Attachment A NIST Statement of Work (SOW)

I. BACKGROUND

The Department of Commerce and the National Institute of Standards and Technology (NIST) have developed a major national facility for neutron scattering. This project provides for over 20 unique instrument stations used by national and international researchers for materials research. In addition, instruments are also provided for fundamental physics research, neutron interferometry, and neutron optics.

To remain at the forefront of science, the NIST Center for Neutron Research (NCNR) is continuously developing new and improved instruments for neutron scattering. The proposed acquisition is part of a redesign of the neutron stress diffractometer located at BT-8 of the NCNR, with the goal of revolutionizing the capabilities of this class of neutron instrument, and to address both the needs of the manufacturing community and to build on NIST leadership in non-destructive testing and engineering research.

II. PURPOSE:

The multi-wavelength monochromator is a key component of the redesigned BT8 instrument providing three different wavelengths and more than double the neutron flux on the sample. Its primary purpose is the maximization signal intensity from the sample through both increasing the neutron flux and increasing the number of sample reflections in the detector from one reflection to up to six. It will be a commercial item with modification, making it the first of its kind worldwide and it has the capabilities to speed up measurement of stresses up to threefold. . The specifications of the multi-wavelength monochromator were developed specifically to allow the accurate measurement of applied stresses in iron and aluminum based sheet metal for automotive lightweighting purposes. The design allows for other settings in which only two wavelengths are available such that magnesium based alloys can also be measured.

III. GENERAL REQUIREMENTS

The measure for demonstrating parallelism is the compound rocking curve measured on a full thickness ( 33 mm) crystal packet (equal parts of [311],[400], [422] crystals) where the full width at half maximum shall be equal or less than 2 0.15=0.3 degree.

+/- 0.15 degrees

≥ 90 mm high 33 mm thickness

IV. Dimensions and design envelope

Figure 1: Schematic of the proposed multi-wavelength monochromator. Note that the number of crystals shown does not represent the actual requirements. Key features shown are: Common zone axis [01-1] of all crystals, stacking sequence, and crystal length of 150 mm minimum. Also given are total height and minimum total thickness.

Figure 2: Left: Definition of the mean scattering direction (MSD) as average of the three scattering directions [311], [400], [422]. Right: schematic of the rocking curve measurement with [311], [400], [422] as Bragg angles for the three planes (311), (400) and (422). Assuming a monochromatic measurement, the compound FWHM is the sum of the three individual rocking curves with the respective Bragg angles subtracted, thus allowing a superposition as depicted on the right, bottom.

V. Deliverables

1) Monochromator with radiation resistant 2-phase, bi-polar DC stepper motor

2) Rocking curve/reflectivity curve (theta vs. intensity) for one crystal each: [311],[400],[422]

3) Measured under the same instrumental conditions (beam size, divergence, /) as in item 2): Rocking curve/reflectivity curve (theta vs. intensity) for a complete crystal packet with equal parts of [311], [400] and [422] orientations, 33 mm minimum total thickness, showing that angular width for each orientation, and angular distance between orientations is in agreement with requirements 4,5 and 6

4) Measured under the same conditions as in item 3), and using the same packet of crystals: asymmetric reflection [400] (belonging to the [311] crystals at (-25.24) degree offset from the surface normal (beam extension); and asymmetric reflection [311] belonging to the [400] crystals, also at (-25.24) degree offset from the surface normal.

VI. Delivery/ Installation

1. The Contractor shall provide all deliverables listed in SOW section V. no later than one (1) year after contract award.

2. Installation shall be performed by government personnel.

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