CALIFES 2015 run preliminary results Maris Tali University

CALIFES 2015 run preliminary results Maris Tali (University of Jyväskylä) Rubén García Alía Matteo Brucoli Wilfrid Farabolini Salvatore Danzeca

Introduction – JUICE mission (ESA) JUpiter ICy moons Explorer - planned for launch in 2022, expected to reach Jupiter by 2030 • Scientific mission at Callisto and Ganymede 3. 5 years • The radiation environment is dominated by the bound electrons in the Jupiter magnetosphere • The electron spectrum also has a high energy component, which extends to higher energies than the spectrum in geostationary orbit • JUICE Red Book, ESA (2014) J. M. Trippe et al. (2015)

Introduction – Radiation Damage • • • Single Event Effects (SEEs) are caused by a single, energetic particle Single Event Upsets (SEUs) are soft errors, and non-destructive, example a bit-flip in a memory The rate of which these upsets occur is described with a crosssection In addition to this the cumulative effects of radiation (TID) cause damage over time and lead to degradation of performance and failures Due to the dominant electron component in the Jovian atmosphere the electron effect on components needs to be evaluated E. Noordeh (2014)

Gold foil activation setup • • • Goal -> measure the electron intensity at the DUT position as no dedicated dosimetry system was installed Dark current beam, 0. 21 n. C, total time 3 h Beam position was confirmed with gafchrom film, beam center off 0. 5 cm on x -axis and 1 cm on y-axis Electron beam produces photons in copper which activate gold foils Au 197(gamma, n) -> Au 196, well benchmarked in FLUKA due to detailed available reaction measurement data, good results were obtained with a similar experiment in Pohang with 2. 5 Ge. V electrons (M. Brugger et al. (2011)) The gamma spectroscopy was performed 7 days after irradiation with a Germanium gamma detector Beam center Foil center

Gold foil activation results • Measurement results: Activity (k. Bq) Error (k. Bq) 1. 030 0. 044 2. 270 0. 096 3. 210 0. 136 FLUKA results: Activity (k. Bq) Error (k. Bq) 9. 897 0. 084 10. 938 0. 097 11. 628 0. 079 Measured 14. 000 FLUKA/3. 4 12. 000 10. 000 Activity (k. Bq) • 8. 000 6. 000 4. 000 2. 000 0 1 2 3 Foil length from z=0 (cm) 4

Gold foil activation conclusion The difference between the measured gold foil activation and the FLUKA simulated activation is a factor 3. 4 • The probable reasons for this are the beam misalignment, also some losses along the beamline due to physical objects in the beamline (instrumentation) • Losses are expected to vary significantly with operation conditions, therefore it is essential to have a dosimetry system at the test location •

Rad. FET measurements setup • • Rad. FETs set up upstream of BTV, shifted 1 cm from the centre of BTV, which is not necessarily the center of the beam Beam in dark current setting (0. 34 n. C) 0. 8 Hz – 23 rd November – total time 28 h 5 Hz – 16 th of November – total time 11 h

Rad. Fet measurements results (Matteo Brucoli) For the 5 Hz – 58 Gy/h was measured For 0. 8 Hz – 9. 8 Gy/h • Theoretical difference in dose corresponds to the measured difference in dose rate • Both measurement show very good linearity with time

Rad. Fet measurement conclusion • Theoretical difference in dose corresponds to the measured difference in dose rate • Both measurement show very good linearity with time Due to the small beam size, the beam gradient is very high. Therefore, dose depends strongly on the exact position of the Rad. FETs FLUKA simulation of dose in Si. O 2 for the 5 Hz case demonstrates the high gradient of the beam, hundreds of times difference in a few cm • •

ESA SEU Monitor tests and setup • ESA Monitor downstream BTV screen, aligned with its center “by eye” • Optimized dark current settings 9 th – 10 th November 16 h (beam current ~0. 31 n. C per train) Weak laser pulse 9 th November (~0. 16 n. C) Dark current 13 th – 16 th November (~0. 28 n. C) • •

ESA Monitor results (R. García) Die 0 Die 1 Die 2 Die 3 9 142 2 70 53 63 105 309 436 787 762 x Weak laser pulse 0. 16 n. C Optimized dark current settings 0. 31 n. C Dark current 0. 28 n. C During all of the runs single event effects were observed • The dark current mode looks most promising for irradiation campaigns, especially with improved beam homogeneity • 1 0 3 2

ESA Monitor results conclusions • • Electrons are capable of inducing SEUs even in technology with a relatively high critical charge compared to modern technology For the optimized dark current run, the cross section could be calculated and corresponds for 309 SEUs and 4 Mbit a cross section of 1. 6 e-18 cm 2/bit (with large uncertainty!) • • • This cross section is 5 orders of magnitude smaller than the proton cross section and about 4 times smaller than simulated value Dark current setting seems promising for radiation testing of electronics, given that the beam is more homogenous Current analysis is still preliminary and a more detailed cross section derivation will require further analysis/measurements

Future work • • • Increased beam size at DUT position, provide a homogenous beam for a standard chip sensitive area (2 x 2 cm), this would mean a FWHM of about 5 x 5 cm Beam instrumentation at DUT position to monitor beam flux during irradiation Extend SEE measurements to a broader set of components and energies Possibility of moving experiments in and out of beam remotely ESA is interested, after beam improvements, in conducting SEE/TID tests at the CALIFES facility

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