Overview of the NPDGamma Experiment at the Fundamental Neutron Physics Beamline

1. Overview of the NPDGamma Experimentat theFundamental Neutron Physics Beamline Geoff Greene UT/ORNL

2. Overview • FNPB Beamline • NPDGamma Experimental Layout • Radiological Shielding • Magnetic Shielding • Issues and Concerns

3. Preliminary Design Review Charge • Have the hazards been completely identified and accurately classified? • Is the design reasonable and does it adequately address identified hazards? • In particular, is the conceptual design for the liquid hydrogen system (target, control system, vent stack) capable of leading to an acceptable final design of the system? • Are the proposed operational parameters and physical characteristics of the hydrogen target system appropriate for safe operation? • Are other aspects of the experiment reasonable and amenable to safe operation?

4. FNPB “Upstream” Beamline Components Shutter Insert Shutter Gate Core Vessel Insert Core Vessel Flange STARTING POINT neutrons

5. FNPB Cold Neutron Beamline Cold Beamline • Guide from 5.5 m to 15 m • Bender out to 7.5 m (R=117 m) Line of sight ends before 2ndary shutter • 4 chopper housings • Monochromator housing • Secondary Shutter • Beam Monitor & Beam Stop

6. FNPB Cold Neutron Beamline Monolith Shielding

7. FNP DESIGN OVERVIEW

8. FNPB Construction Status 6/07Project is currently on schedule

9. FNPB Shield Wall

10. FNPB Cold Beamline Status The FNPB Cold Beamline design is essentially complete. Remaining tasks are completion of shielding enclosure detailed design, PPS, and utilities layout. We are NOT explicitly asking for a review of these components.

11. The NPDGamma Experiment Supermirror polarizer CsI Detector Array Liquid H2 Target H2 Vent Line H2 Manifold Enclosure Magnetic Shielding FNPB guide Magnetic Field Coils Beam Stop

12. The NPDGamma Experiment – Vent System

13. The NPDGamma Experiment – Shield Roof and Mezzanine

14. The NPDGamma Experiment – Vent Line Routing

15. Radiological Shielding NOTE: Because of curved guide and use of 6Li collimation, dose rates are totally dominated by photons by cold neutron capture.* Shielding enclosure: 18” Concrete shared wall with FP 12 9” Concrete wall on FP 14 side 9” Concrete roof Enclosure is lined with Steel (up to 2” in places) Additional “temporary” shielding blocks are placed on FP14 of Wall *This is validated by MCNPX simulaltions.

16. MCNPX Radiation Simulations

17. MCNPX Radiation Simulations

18. Magnetic Fields The NPDGamma magnetic field is low (10 Gauss) but occupies a large volume. The shielding enclosure is lined with 0.25”-0.75” of 1010 steel to act as a flux return. This also serves to provide magnetic shielding and to confine stray magnetic fields. We used commercial magnetic FEA software (OPERA3D) to model our magnetic field arrangement. Facility requirements call for magnetic field to be less than 50mGauss at the boundary of adjacent beamlines

19. Stray Magnetic Fields -Summary FP 14 side FP 12 side 788.72 348 30.5 A 1 Concrete wall 133 • Coils 152.2 E F 90.8 Z 182.68 303.83 331.65 225 X Concrete wall Magnetic shield B 359.2 2 30.5 440.72 The NPDGamma external magnetic field is below the facility required level at the FP12 boundary and the FP15 boundary. It slightly exceeds the required level at the FP14 boundary. This is acceptable to FP14 beamline responsibles.

20. Other Issues A detailed hazard screening (next presentation) has identified the liquid Hydrogen target as the only “exceptional” operational issue. All other hazards are similar to those encountered on other SNS instruments. The details of the LH2 target and vent system are the subject of the third presentation.

21. The NPDGamma Experiment Supermirror polarizer CsI Detector Array Liquid H2 Target H2 Vent Line H2 Manifold Enclosure Magnetic Shielding FNPB guide Magnetic Field Coils Beam Stop

22. End of Presentation