CODIF CORSS-CALIBRATIONS C. Mouikis, L. Kistler, K. Genestreti UNH 10th CAA Cross-Calibration meeting L'Observatoire de Paris, Paris, 2-4 November 2009

From Last Cross-Calibration meeting Efficiency Summary Efficiencies have been checked through Jan SC4 shows a significant decline at the end of We need to increase MCP voltage. Calibrated data in CAA (goes through 2005) is good, both in relative and absolute efficiency (from both Whisper comparisons and pressure tests) For Anode efficiencies are good (Vz looks nominal) HS/LS comparison looks good SC3/SC4 comparisons look good. The Absolute efficiency still looks too high (pressure coming out too low). This needs to be adjusted before release.

Efficiencies - Temporal changes MCP increase on CODIF on SC4 in July 2009

Timeline of MCP increase SC4 CODIF :26152 to :28154 to :42HV reduced - inner belt : :24152 to :54154 to :58reset and back to :41156 new operational value

MCP HV from 152 to 154 MCP HV change

MCP HV test at

SC4/FM7 Efficiencies start stop Single event 5 yrs (since last increase)Whole Mission

Total H+ Efficiency for SC4 5 year SC4-linear scaleSC4-log scale

Total H+ Efficiency for SC4 Whole Mission SC4-linear scaleSC4-log scale

SC4 MCP increase -Conclusions The increases brought the efficiency up by about a factor of 2. The efficiency level is about where we were in the summer of All voltages and currents looked stable Overall, data looks very nice. Should be a great tail season!

Efficiencies have been checked through Jan SC4 shows a significant decline at the end of We need to increase MCP voltage. Calibrated data in CAA (goes through 2005) is good, both in relative and absolute efficiency (from both Whisper comparisons and pressure tests) For Anode efficiencies are good (Vz looks nominal) HS/LS comparison looks good SC3/SC4 comparisons look good. The Absolute efficiency still looks too high (pressure coming out too low). This needs to be adjusted before release. From Last Cross Calibration meeting Efficiency Summary

Plasma sheet Pressure Balance Tests Black - SC4 CODIF, Blue+Red SC1/3 HIA Particle Magnetic Total P

Plasma sheet Pressure Balance Tests Black - SC4 CODIF, Blue+Red SC1/3 HIA Particle Magnetic Total P

Plasma sheet Pressure Balance Tests Black - SC4 CODIF, Blue+Red SC1/3 HIA Particle Magnetic Total P 2007

CODIF Efficiencies Relative efficiency change at different positions for SC 3 and SC4, H+ and O+ Use pitch angle spectra during gyrotropic time periods to normalize the different positions within each instrument. This is done separately for H+ and O+ Overall Change in H+ Efficiency Changes. For SC4 (FM7) use “monitor rate” data to track the start efficiency (SFR/SR), stop efficiency (SFR/SF) and the fraction of coincidences that also have a single position signal (SEV/SFR). The product of these values gives the total efficiency. For SC3 (FM6) (for which the Stop rate, SR, does not work well) use comparison spectra with FM7 for time periods when the two spacecraft are close. Overall Change in O+ We used to use times when the count rate was dominated by O+ (mainly times with O+ “beams” in the lobe). Because these now only rarely give a sufficiently high count rate, we instead use comparison O+ spectra between SC3 and SC4, and assume that SC3 is constant

Pressure Balance Test used to track the SC4 H+ total efficiency for The H+ efficiency is adjusted so that pressure balance is achieved when the S/C transitions from the Plasma Sheet to the Lobes and back

Pressure balance deduced absolute efficiency correction Efficiency

Calibration Files Where are we know New Calibration files have been made that cover 2006 and This includes updates to HS H+ total and position efficiencies updates to HS O+ total and position efficiencies We have done / are doing the following checks Comparison of moments in plasma sheet - spot checks and statistical averages (average velocities, densities) Checks on LS at times when instrument switches from LS to HS Absolute Calibration Tests Comparisons with PEACE - Whisper - SC/P - WBD

SC4 / SC3 moments comparison 2006 GSE Coordinates Instrument Coordinates / Half instrument The Vz component on SC3 is not measured because one half of the “high side” is not working

SC4 / SC3 moments comparison 2007 GSE Coordinates Instrument Coordinates / Half instrument

CODIF / HIA comparison The velocity components agree. The CODIF density is higher by a factor of ~

CODIF / HIA comparison The velocity components agree. The density agrees as well

CODIF/HIA Density ratio over the mission time The CODIF/HIA density ratio has dropped in recent years by a factor of 2. What has changed?

CODIF cross - calibrations with other experiments We want to monitor the total MCP efficiency level We use PEACE, SC/P and WHISPER to confirm levels of MCP efficiency We are not comparing quantities that owe to be equal.

CODIF (black) / PEACE(green) Example #1

CODIF (black) / PEACE(green) Example #2

CODIF (black) / PEACE(green) Example #3

CODIF/PEACE density ratio over the mission time Comparisons with PEACE show relative agreement though for 2006 there is a trend to by looked at.

CODIF (black) - WHISPER (red) - PEACE (green) comparisons Example #1

CODIF (black) - WHISPER (red) - PEACE (green) comparisons Example #2

CODIF (black) - WHISPER (red) - PEACE (green) comparisons Example #3

CODIF/WHISPER comparisons plan Comparisons with WHISPER in the plasma sheet can be very useful for the determination of our absolute efficiencies because they can provide “anchor” points. From early years we have examples of spot-on agreement We’ll request some events, three per year, from 2006 onwards. We’ll use the S/C potential deduced density in order to make sure that there is a good chance that WHISPER and CODIF are measuring the same population WHISPER team will provide advice on the event selection

CODIF (black) / WBD (blue) Density comparison

Summary The MCP voltage increase brought the efficiency up by a factor of 2. Calibrations for are finished and we are in the testing stage Comparisons with the HIA densities show a decrease in the “traditional” factor of discrepancy. Comparisons with PEACE show relative agreement though for 2006 there is a trend to by looked at. Comparison with WHISPER deduced densities can give as “anchor” points to test our MSP efficiency levels Attempted to use WBD deduced densities