HyperK Geometry for WCSim Peter Gumplinger TRIUMF Simulation

Hyper-K Geometry for WCSim Peter Gumplinger - TRIUMF Simulation Software Support Scientist Geant 4 Collaboration - Author of optical Module Abstract: This talk describes the implementation details of a Geant 4 geometry model for the baseline design of the Hyper-K detector. 2 nd Open Hyper-K Meeting Kavli IPMU, Kashiwa City, Japan 14 -15 January 2013 1

Baseline Design - Salient Features • 2 separate caverns • egg-shape cross section • 5 optical separated compartments per cavern • Compartment optically separated into 3 regions: inner, outer, and middle/dead space 2

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Water Level Cavern Cross Section • R_Top > R_Bottom • Centre_Top != Centre_Bot • PMTs facing to/away from centre of curvature • Side: inner PMT on equator • End: inner PMT on horizontal line 4

Water Tank Slice == G 4 Subtraction. Solid(G 4 Tub - G 4 Box) Construct Half (top or bottom): Centre == G 4 Trap Union 1 == G 4 Union. Solid(G 4 Trap + Slice(pos 1)) Union 2 == G 4 Union. Solid(Union 1 + Slice(pos 2)) Water. Tank == G 4 Union. Solid(Top+Bottom) 5

Side Wall PMT Arrangement c a b d 6

Side Wall PMT Arrangement b Construct. Radial. PMT (inner/outer & top/bottom) annulus = G 4 Tubs d ring = G 4 PVReplica(annuls, k. ZAxis, nz, pitch. Z) cell = G 4 PVReplica(ring, k. Phi, nphi, dphi, -phi/2) 7

Side Wall PMT Arrangement 8

Side Wall PMT Arrangement 9

Side Wall PMT Arrangement Thin walled Cylinder: - in WCSim is rendered as a G 4 Polyhedra (Trapezoid) - for HK egg shape sides rendered as phisection replicas of G 4 Tubs (cylinder) 10

End Wall PMT Arrangement 11

End Wall PMT Arrangement Construct. End. Wall. PMT Slab (establish vertical length): while(x<xmas) while(y<ymax) if(diagonal > radius_top)break if(diagonal > radius_bot)break; (increment pitchy) G 4 PVReplica(Slab, k. YAxis, ny, pitchy) 12

End Wall PMT Arrangement 13

PMT G 4 Sensitive. Detector == logic. Glass. Face. WCPMT (in WCSim) its name is expected to be “Glass. Face. WCPMT” 14

Cerenkov Ring 15

Monte Carlo Tuning Optical Properties: Water: Refractive Index, Absorption Length, Rayleigh Scattering Length, and Mie Scattering Length Glass: Refractive Index, Absorption Length Cathode Surface: Reflectcivity Black Sheet: Reflectivity, Surface Roughness Surface: Border. Surface in WCSim / replace with Skin. Surface (also for World volume) for the Black Sheet 16

Implementation (done) – Geometry: Water Volume, PMT Arrangement, Black Sheet Integration Details (not yet done - needs discussion) – WCSim uses FORTRAN style “if(){…}elseif(){…} and a proliferation of class data members describing all geometry options. – change to proper C++ class inheritance: base class and derived classes for each detector geometry implementation. 17

Conclusion • A close working relationship between Monte Carlo simulation and technical design teams is desirable. In particular, to avoid non-essential design decisions that may impact computing performance. (PMTs in the horizontal plane) Next Steps • What is the Panel layout for the Side PMTs? • Merge with WCSim • Run some events and analyze (Root Geometry) 18