Applications of Geant 4 John Allison HEP Xmas

Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 1

Geant 4 Associates • Not-for-profit company 2007 – to enable us to continue working on Geant 4 – to promote Geant 4 • Contracts – JUNO (NASA mission, star tracker camera shielding) – ESA Biological effects – ESA Electron shielding – SPEAR (ESA radiation monitor) – Kromek (X-Ray scanners Applications of Geant 4 John with Allison HEPCd. Te detectors) November 29, 2020 2 Xmas Meeting 20 -21 December 2010

JUNO Star Tracker project • NASA – Galileo Avionica – Manchester (Steve Watts, Mahfuza Ahmed, Ray Thompson, John Allison) • Experimental exposure of CCD to electron and proton beams (Steve) • Simulation of Star Tracker and simulation and analysis of experiments (John) November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 3

JUNO Launch Window Opens Aug. 5, 2011 Key things to know about Juno Spacecraft launches in August 2011 Five-year cruise to Jupiter, arriving July 2016 One year at Jupiter will complete the mission (orbiting the planet 32 times) November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 4

JUNO interplanetary cruise November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 5

JUNO Star Tracker Geant 4 cutaway • Star tracker takes 4 frames per second • Rolling readout of CCD as spacecraft rotates at 12 rpm • Images matched against on-board star map • Essential for navigation • Must survive mission • 3 trackers built, 2 installed November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 6

JUNO Star Tracker crosssection Green = tungsten added for this mission because of high radiation as indicated and then modelled by Geant 4 studies November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 7

JUNO Star Tracker crosssection CCD yellow November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 8

Geant 4 simulation Above 200 Me. V, shielding makes deposited energy worse due to production of multiple secondaries in an electromagnetic shower November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 9

Test beam model • 20 μm Havar • Collimator with variable thickness of tungsten—see next slide • 59. 5 cm air • Gafchromic film (and support) • Mylar window • Cryostat front face • Preamplifier shield • CCD 23 rd September 2008 John Allison University of Manchester SEU simulation 10

Worst case image 200 x 200 portion November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 11

Worst case image 512 x 512 November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 12

Radiation background • Proton from solar flares (3 assumed) • Electrons and protons from Jovian radiation belts – High energy (peak at 40 Me. V, tail to 1 Ge. V) – Highly elliptical 10 -day orbit – Passes through densest belt for only a few hours, or even minutes, in 10 days – Requirement: out-time due to background must be less than 30 min total – 10, 000 hours Geant 4 CPU time—no fake stars!! • (after comparing with star maps) November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 13

Radiation damage • Ionising energy loss – Mainly Jovian electrons: many k. Rad but OK – CCD is a highspecification radiation-hard device • Non-ionising energy loss (NIEL) – Gives rise to displacement damage dose (DDD) – Major contribution from neutrons, secondaries from both electron and proton interactions in the shielding – Bremsstrahlung from electrons produces neutrons by photoproduction. – Electrons produce neutrons directly by electro-production • of available simulation codes, only Geant 4 modelled this process – Overall, the DDD from electrons is roughly same as from protons – CCDs are very sensitive to displacement damage—this turned out to be the Applications limitingof factor for star Geant 4 John Allison HEP tracker lifetime November 29, 2020 14 Xmas Meeting 20 -21 December 2010

SPEAR (Space Plasma Environment And Radiation) detector • Mullard Space Science Laboratories (MSSL) – Manchester (Cinzia Da Via, Steve Watts) – G 4 AI collaboration • Micro-Electro-Mechanical Systems (MEMS)-based • Highly Miniaturised Radiation Monitor (HMRM) • Marriage of 3 D detector (Manchester) and Medipix pattern recognition chip behind sophisticated collimator and attenuator plate • G 4 AI to simulate response to various radiation fields November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 15

Detector – Medipix bonding High resistivity silicon to be replaced by 3 -D sensors November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 16

Silicon in electron field November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 17

Energy deposited November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 18

Collimator attenuator plate November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 19

With collimator/ attenuator plate 5 mm aluminium to rear and 5 mm silicon to sides to mimic space craft and surrounding electronics November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 20

1 Me. V isotropic electrons Weighted by energy deposited 640 million events generated 1175128 events detected November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 21

SPEAR status • Phase I (feasibility) report submitted – Awaiting ESA judgment • Phase II: build prototype – Hopefully next year November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 22

Geant 4 availability and help • 9. 3 is installed on Linux machines • 9. 4 released last week – Yet to be installed • Growing number of users • Growing number of “experts” • Always willing to help – just email or Skype – John. Allison@g 4 ai. org or John. Allison 1 @ Skype November 29, 2020 Applications of Geant 4 John Allison HEP Xmas Meeting 20 -21 December 2010 23