November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 1 DLR 03 – RAD Sensor Head (RSH) Functional Overview Robert F. Wimmer-Schweingruber, IEAP/CAU, Kiel, Germany RAD Packaging Review

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 2 DLR RAD Level 2 Science Requirements RAD Science Requirements: RAD shall measure energetic charged particles (Z=1-26) with energies up to 100 MeV/nucleon. RAD shall measure neutral particles (neutrons and gamma- rays) with energies up to 100 MeV RAD shall measure energetic electrons with energies up to 10 MeV. RAD shall measure dose and LET spectra on the Martian surface.

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 3 DLR RAD shall measure energetic particles with an energy resolution sufficient to distinguish between major particle species (i.e. protons, He), low Z(i.e. p, He, Li ions), medium Z(i.e. C, N, O ions), and high Z (i.e. heavier nuclei up to Fe) particles. RAD shall measure energetic particles with time resolution sufficient to obtain time series observations over the course of the MSL baseline mission and to resolve spectra associated with solar particle events when they occur. RAD Level 2 Science Requirements (cont’d)

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 4 DLR Charged Particle Interaction with Matter Ionization electron content important heavy ions deliver more dE/dx dE/dx ~ Z p 2  /E...

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 5 DLR Summary of Measurement Requirements Charged particles (Z = 1–26) up to 100 MeV/nuc Neutral particles (n,  ) up to 100 MeV/nuc Electrons up to 10 MeV LET Species discrimination Time series Autonomous operation

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 6 DLR RAD Sensor Head (RSH) n-Measurement Principle Thus need transparent high-proton-content material

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 7 DLR n-Measurement Approach Neutron Channel: Conversion of neutrons to detectable protons using 30 g of high proton-content- scintillator (BC432(m)) Neutral particle detection requires efficient anti coincidence (AC) MIPs energy deposit 2 MeV/g/cm 2 → use 12mm BC432(m) Need ≥ 99.8 % efficiency, no crosstalk, light tightness

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 8 DLR n-Measurement Approach Don't want high voltage in Martian atmosphere. → Read out light signal with PIN diodes. Use same detectors as for charged-particle telescope. → Resolve very small signal. → Need good CSAs. background muon signal

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 9 DLR  -Measurement Principles Thus need transparent high-density material Photo-effect Compton effect Pair production

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 10 DLR  -Measurement Implementation MSL RAD CsI- crystal CsI is a very efficient  detector, moreover, 30 mm CsI stops 100 MeV protons and 200 MeV/nuc iron. Signal read out with PIN diodes. Test diode (non flight)

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 11 DLR n-  -Measurement Implementation Keep CsI calorimeter (D) and n-channel (E) close together and inside telescopoe FOV for charged particle measurements. Stack must be inside efficient AC. n Separation of n and  by statistical method similar to a method also applied to SOHO data (Böhm et al., 2006)  D E

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 12 DLR Statistical Separation of n and  -rays by Matrix Inversion

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 13 DLR Measurement Implementation Solar particle event measurement requires maximization of geometric factor: FoV Active Area Particle discrimination FOV half-angle  60° Simulations and other considerations:  = 32.5 deg. Results in acceptable path-length variations. CsI thickness 28 mm results in 100 MeV/nuc stopping power for most particles. 

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 14 DLR RSH SSD Geometry Three SSDs allow limited dE/dx close gaps in anti-coincidence A B C D E F B C D F

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 15 DLR **The RTG will induce a background to the neutron and  -ray channels, which will be characterized during cruise phase for improved background subtraction. *SPE count rates will be 10 – 1000x greater depending upon the flux and spectrum of the event. Expected RAD Count Rates (GCR only)

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 16 DLR RAD Performance: RTG background Tl MeV Pu MeV S.E MeV D.E MeV Pu MeV

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 17 DLR RAD RSH Measurement Requirements Summary c: calibration, h: heritage, s: simulation, t: tests Requirements and Expected Performance

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 18 DLR RSH Model philosophy Pathfinder unit built flight-like, but no qualification standard. For CAU-internal testing and process development purposes only. Engineering model: flight-quality model, qualification unit for all RSH qualification tests. Flight model: test only to acceptance level. Flight spare: same standards as flight model, use for full calibration (refurbished engineering model is currently only carried as a backup option)

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 19 DLR RSH Overview Summary CsI energy/thermal response characterized RSH modelling ongoing and assuring Manufacturing ongoing Pathfinder SSD delivery imminent Flight SSD bonding to wait for Pathfinder Thermal test chamber delivered 2 diploma theses completed

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 20 DLR RSH Overview Summary Backup Slides

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 21 DLR RAD Sensor Head Overview Institute for Experimental and Applied Physics (IEAP), Kiel University Experience: Helios, ISEE-2, Galileo, Ulysses, SOHO, STEREO Dostel (ISS), Matroshka, EUTEF Facilities: fully equipped machine shop, electronics shop calibration facilities Funding: Deutsches Zentrum für Luft- und Raumfahrt (DLR) (to 12/09) German Science Foundation (DFG) Personnel: experienced (state-funded) personnel in group (9) and machine shop (13) plus project-funded scientists and engineers

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 22 DLR RAD Science Requirements

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 23 DLR GCR Interactions with the Atmosphere Secondary production Energy input

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 24 DLR RSH Overview Summary Planetocosmics: A GEANT 4 application for tracking particles in the vicinity of a planet particle propagation through the Planets atmosphere Visualization of tracks incl. production of secondaries Calculation of the energy depositions Calculation of the fluxes of secondaries, e.g. neutrons Calculation also in the presence of relic crustal magnetic field

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 25 DLR Preliminary Simulations Pfotzer Maximum at Earth is at about 20 km Pfotzer Maximum on Mars is at surface level

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 26 DLR n-Measurement Implementation MIPs deposit very little energy in anti-coincidence. Therefore, to reach high A/C efficiency, we need to understand: peak shape background energy deposit Measured pure cosmic muon signal in BC-430 anti- coincidence (A/C) material. low energy deposit insert energy

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 27 DLR n-Measurement Implementation Background in detectors results in partial hiding of MIPS signal. background muon signal High-efficiency A/C triggering on MIPs requires running into background to get all MIPs.

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 28 DLR n-Measurement Implementation measured efficiency curve “100%” efficiency at low E-channels 99.8% anticoincidence efficiency demonstrated

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 29 DLR  -Measurement Implementation

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 30 DLR  -Measurement Implementation

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 31 DLR RAD Performance: RTG background

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 32 DLR RAD Performance: RTG background RAD single detector count rates (estimation) inner 2 segments45 counts/s7 counts/s60 keVPIN Photo-diode C 300 µm, 2.3 cm 2 middle segment, anti-coinc.30 counts/s5 counts/s60 keVPIN Photo-diode C 300 µm, 1.5 cm 2 outer 3 segments with BC430 cylinder 190 counts/s counts/s 30 counts/s + 2 counts/s 60 keVPIN Photo-diode C 300 µm, 10.1 cm 2 inner segment35 counts/s6 counts/s60 keVPIN Photo-diode B 300 µm, 1.9 cm 2 inner 2 segments45 counts/s7 counts/s60 keVPIN Photo-diode A 300 µm, 2.3 cm 2 outer 4 segments, anti-coinc.210 counts/s35 counts/s60 keVPIN Photo-diode A 300 µm, 11.6 cm 2 RemarkWith RPSWithout RPSThresholdDetector

November 30, December 1, 2006 MSL RAD Sensor Head (RSH) peer review 03 – RAD Sensor Head (RSH) Overview RAD – The Radiation Assessment Detector for MSL Wimmer-Schweingruber 33 DLR RAD Performance: RTG background RAD single detector counting rates (estimation, continued) worst case area 40.0 cm counts/s **2 counts/s **150 N photo-electrons BC430 Cylinder, anti-c. 50 mm high worst case area 66.5 cm counts/s2 counts/s150 N photo-electrons BC430 Scintillator F 12 mm high worst case area 20.4 cm counts/s1 counts/s150 N photo-electrons BC430 Scintillator E 18 mm high worst case area 10.6 cm counts/s1 counts/s40 N photo-electrons *CsI Scintillator D 28 mm high RemarkWith RPSWithout RPSThresholdDetector * Threshold does not drive the design, somewhat arbitrary ** Counted in detector C (outer 3 segments)