Werner Schweika, Nicolo Violini, Earl Babcock Michael Meissner Andreas Houben, Philipp Jacobs Gunnar Svennson, Xiaodong Zou, Niklas Hedin, Mats Johnsson, Jekabs Grins, German Salazar-Alvarez Graeme Blake, Thomas T.M. Palstra Mari-Ann Einarsrud Raphael Hermann Reinard K. Kremer D REAM Powder Diffractometer at the ESS D REAM Diffraction Resolved by Energy and Angle Measurements SAC 11 Lund May 23 rd 2014 Klaus Lieutenant, Carolin Zendler, Daniil Nekrassov VITESS Neutron guide simulators

Neutron guide system 75 m long bispectral - thermal and cold neutrons Bi-spectral switch of Si-wafer for cold neutrons ~6cm, T~0.8 Optimization for λ min = 0.5 Å (initially for 0.8Å) Q max < 25 Å -1 1 cm 2 beam cross-section at sample divergence +/ o cost (backtracing for optimal m-coating) Concept (hidden) double ellipses eye-of-needle at pulse shaping chopper (6+x m) minimizes background straight guide axis + T0 chopper T0 chopper early in a guide free section Pancake Vertical part needs to be adapted shift focus to source start at 2m from source => nearly ideal gain for 3cm high pancake moderator VITESS work by Nicolo Violini, Carolin Zendler, Klaus Lieutenant

D REAM Moderator cold thermal light shutter bispectral switch OV BC BC Chopper PS T0 elliptic - ballistic guide 60 mm x 60 mm 0 m 6.11 m 6.10 m m m m= cm 2 m=2.5 m= m 8.00 m12.75 m Instrument Shutter m variable collimation m Detector m m m Monitor Beam Stop Laue station

A. Houben et al NIMA, 2012, 680, 124. vertical horizontal cm Å λ 2.8 Å 4.6 Å 0.25 o o 0.25 o Nicolo Violini Neutron guide simulations 2014 Pancake moderator Carolin Zendler & Nicolo Violini full gain! VITESS optimized coating now for λ = 0.5 Å Concept

Hz / 14 Hz 14 Hz T0 chopper BC chopper guide light shutter monolith bispectral extraction system Choppers Pulse shaping double disc chopper near the needle’s eye

Source and Extraction System –Source ESS Thermal and cold moderator side by side, 12 x 12 cm each Characteristics from May 2013 (Schönfeldt) Wavelength: Å Time range: 0.0 – 7.0 ms Illuminated area in 565 cm distance: – x cm² (chopper options 1 – 3) – x cm² (chopper options 4 – 6) Stack for bi-spectral extraction Position: cm from source Mirror size 25 cm length 12 cm height (larger than needed) Number of mirrors : 23 Distance of mirrors: 2.59 mm Coating : m=3 Inclination: 0.594° 0.5 mm silicon absorption as measured for single crystals of 300 K (A. Freund, NIM 213 (1983) 495 [1]) Klaus Lieutenant

Bender-Design and Position 7 R α L α D bend w α = atan(w/D bend ) = α = L/R Criterion for at least 1 reflection: R ≤ L²/8d =>R ≥ 8d/α L ≥ 8d/α For w=12 cm, D bend =605 cm, λ cross =2.0: α = = 1.136° R = 3051 mm, L = mm, d=0.15 mm m= 2.87 m= 0.5α/(0.1° λ cross ) Klaus Lieutenant

Efficiency of Bender and Mirror Stack 8 Klaus Lieutenant

9 PowHow: Beamline 12x12 cm² 0 m76.50 m m 12x12 cm² 5.65 m23.70 m58.90 m 19 x 19 mm²10 x 10 mm² m=0m= m 60 x 60 mm² m=2 Guide: square cross-section 2 half ellipses of 17.6 m and 30 mm half axes with focal points at virtual source and sample position, connected by a straight guide Part 1: – m ( > cm W, H) from 1 st focal point Part 2: m straight guide of x cm² cross-section Part 3: m ( > cm W, H) from 2 nd focal point Collimation: +/ °: 4.58 m from sample: 2 x 458 cm tan 0.250° = 4.00 cm = W guide (71.92 m) +/ °: m from sample: 2 x 1327 cm tan 0.125° = 5.79 cm = W guide (63.23 m) m=

Pancake optimization Focal point vertically in source Coating m=5 not yet optimized Carolin Zendler

Costing in proposal of the neutron guide system: The costing estimate is based on the recent company information. The neutron guide is a double elliptic, straight guide with high m-coating (3.2<m<7) optimized to transport neutrons of 0.5 Å wavelength. The costs for the 70m long guide, vacuum housing, support system, installation of the guide system amount to Euro. Costs for the vacuum pumps and vacuum control systems are estimated to Euro. The optical component for the bispectral extraction in the solid-state bender version is estimated to Euro. Sum: Euro