CODIF StatusCODIF Status

Lynn Kistler, Chris MouikisLynn Kistler, Chris Mouikis

Space Science CenterSpace Science Center

UNHUNH

July 6-8, 2005Paris, France

OutlineOutline H+ EfficienciesH+ Efficiencies O+ EfficienciesO+ Efficiencies Moments comparisonsMoments comparisons Comparisons with FAST/TEAMSComparisons with FAST/TEAMS

H+ EfficienciesH+ Efficiencies Temporal Changes.Temporal Changes.

The temporal changes in the absolute efficiency are The temporal changes in the absolute efficiency are determined using the “Monitor Rates”determined using the “Monitor Rates”

Start rate (SF)Start rate (SF) Stop rate (SR)Stop rate (SR) Coincidence Rate (SFR)Coincidence Rate (SFR) Single event rate (SEV)Single event rate (SEV)

These allow us to monitor the start efficiency (SFR/SR), These allow us to monitor the start efficiency (SFR/SR), stop efficiency (SFR/SF) and the fraction of coincidences stop efficiency (SFR/SF) and the fraction of coincidences that also have a single position signal (SEV/SFR).that also have a single position signal (SEV/SFR).

The product of these values gives the total efficiency.The product of these values gives the total efficiency. The stop rate (SR) is not completely reliable, which gives The stop rate (SR) is not completely reliable, which gives

some uncertainty in the final answer.some uncertainty in the final answer.

Temporal ChangesTemporal Changes Following the last meeting, the MCP voltages Following the last meeting, the MCP voltages

were increased as follows:were increased as follows: July 12 and 24, 2004: All SC increased two steps. July 12 and 24, 2004: All SC increased two steps.

(values SC1/150, SC3/150, SC4/150)(values SC1/150, SC3/150, SC4/150) Result - OK, on all spacecraftResult - OK, on all spacecraft

Sept 25, 2004: All SC increased two steps (values Sept 25, 2004: All SC increased two steps (values SC1/152, SC3/152, SC4/152)SC1/152, SC3/152, SC4/152)

Result - some discharges in SC3 - reduced to 150 on Result - some discharges in SC3 - reduced to 150 on 10/12/0410/12/04

SC1/FM8 EfficienciesSC1/FM8 Efficienciesst

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1-year Whole mission

SC4/FM7 EfficienciesSC4/FM7 Efficienciesst

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SC3/FM6 EfficienciesSC3/FM6 Efficienciesst

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Total Efficiency for all Total Efficiency for all SpacecraftSpacecraft

Separate Anode EfficienciesSeparate Anode Efficiencies In order to accurately measure the velocities In order to accurately measure the velocities

and pitch angle distributions, the efficiencies and pitch angle distributions, the efficiencies of individual anodes need to be known.of individual anodes need to be known.

This is determined by using time periods when This is determined by using time periods when the ion distribution is expected to by the ion distribution is expected to by gyrotropic, and normalizing the anodes so that gyrotropic, and normalizing the anodes so that they are the same at the same pitch angle.they are the same at the same pitch angle.

SC1 Anode Efficiencies SC1 Anode Efficiencies One month before anomalyOne month before anomaly

SC4 Anode Efficiencies SC4 Anode Efficiencies Dec, 2004Dec, 2004

SC3 Anode Efficiencies SC3 Anode Efficiencies Feb, 2003Feb, 2003

Anodes 5-8 are so far below theother anodes that it is almost impossible to calibrate them.

In addition, including them adds spikes to the data, because one count converts to such a high flux.

Therefore, we decided to no longer include anodes 5-8 when calculating fluxes. Any counts are zeroed, using the calibration files.

SC3 pitch angle SC3 pitch angle distributiondistribution

Note that SC3 still produces very good data using anodes 1-4.

In most cases it still measures a complete pitch angle distribution (depends on field configuration).

The main loss is the measurement of Vz.

Separate Anode Efficiencies Separate Anode Efficiencies ConclusionsConclusions

SC4 and SC1 (up to the anomaly) SC4 and SC1 (up to the anomaly) Difference between anodes can easily be accounted Difference between anodes can easily be accounted

for in the calibration files.for in the calibration files. For SC3For SC3

the difference between anodes 1-4 and 5-8 is so big the difference between anodes 1-4 and 5-8 is so big that we can no longer accurately determine the that we can no longer accurately determine the anode 5-8 efficiency. anode 5-8 efficiency.

Because the efficiency is so low, single counts Because the efficiency is so low, single counts observed on these anodes are calculated as a very observed on these anodes are calculated as a very high flux and introduce spikes on plots vs timehigh flux and introduce spikes on plots vs time

Anodes 1-4 are still quite good, and in most areas we Anodes 1-4 are still quite good, and in most areas we still get complete pitch angle distributions using half still get complete pitch angle distributions using half the instrument.the instrument.

Therefore, starting on Feb 24, 2003, we no longer Therefore, starting on Feb 24, 2003, we no longer include anodes 5-8. These anodes are zeroed out in include anodes 5-8. These anodes are zeroed out in the efficiency files.the efficiency files.

Programs which calculated flux need to be changed Programs which calculated flux need to be changed so that the calculation assumes only anodes 1-4 are so that the calculation assumes only anodes 1-4 are included.included.

O+ EfficienciesO+ Efficiencies

Anode Efficiencies.Anode Efficiencies. Anode efficiencies can be determined in exactly the same way Anode efficiencies can be determined in exactly the same way

they are for H+: by using time periods when the distribution is they are for H+: by using time periods when the distribution is gyrotropic and there is sufficient O+ flux. This works well, and gyrotropic and there is sufficient O+ flux. This works well, and the results are similar to O+the results are similar to O+

Absolute Efficiencies.Absolute Efficiencies. To determine absolute efficiencies, we need time periods when To determine absolute efficiencies, we need time periods when

the composition is almost pure O+. To do this we use the time the composition is almost pure O+. To do this we use the time periods when we see O+ beams in the polar cap.periods when we see O+ beams in the polar cap.

Since the beams are normally observed in only one anode, we Since the beams are normally observed in only one anode, we then use the anode efficiencies to normalize the measurement then use the anode efficiencies to normalize the measurement to the whole instrument.to the whole instrument.

The beam procedure is done using SC1. We then use The beam procedure is done using SC1. We then use comparisons between SC to get the absolute efficiencies for SC3 comparisons between SC to get the absolute efficiencies for SC3 and SC4.and SC4.

SC1 O+ EfficiencySC1 O+ Efficiency

O+ efficiency using O+ beam data

SC3 and SC4 O+ EfficiencySC3 and SC4 O+ Efficiency

Plasma Sheet - 2003 CODIF Plasma Sheet - 2003 CODIF HH++

SC1, SC3, SC4

•The density shows a good agreement between all SC

•The velocity components from SC3 don’t agree because only one hemisphere is used

Plasma Sheet - 2003 CODIF HPlasma Sheet - 2003 CODIF H++

One hemisphere - Instrument One hemisphere - Instrument coord. coord.

SC1, SC3, SC4 • Here moments from the 3 SC in instrument coordinates, calculated using the one hemisphere (top) are plotted

• All moments show a good agreement confirming that the SC3 top hemisphere provides good data.

Plasma Sheet - 2003 CODIF OPlasma Sheet - 2003 CODIF O++

1 – 40 keV – Instrument coord.1 – 40 keV – Instrument coord.

SC1, SC3, SC4

Plasma Sheet - 2004 CODIF HPlasma Sheet - 2004 CODIF H++

One hemisphere – Instrument One hemisphere – Instrument coord.coord.

SC1, SC3, SC4

Plasma Sheet - 2004 CODIF OPlasma Sheet - 2004 CODIF O++

1 – 40 keV – Instrument coord.1 – 40 keV – Instrument coord.SC1, SC3, SC4

2003 CODIF – HIA 2003 CODIF – HIA Comparison Comparison

SC1 - CODIF, SC1 - HIA

• Comparison between CODIF and HIA moments for SC1

• The density calculated by HIA, inside the magnetosphere, is lower by a factor of ~2 compared to the CODIF density

•The velocity components show a good agreement

2004 CODIF – HIA 2004 CODIF – HIA ComparisonComparison

SC1 - CODIF, SC1 - HIA

Efficiency SummaryEfficiency Summary

H+ and O+ HS efficiencies have been H+ and O+ HS efficiencies have been calculated through the end of 2004. The calculated through the end of 2004. The files are available.files are available.

SC4 continues to operate very wellSC4 continues to operate very well SC3 works well on one half. Using that half SC3 works well on one half. Using that half

we can get reliable fluxes, densities, we can get reliable fluxes, densities, temperatures and pitch angle distributions. temperatures and pitch angle distributions. Vz cannot be measured.Vz cannot be measured.

SC1 worked very well until the anomaly. We SC1 worked very well until the anomaly. We hope that we will get it operating again soon.hope that we will get it operating again soon.

Comparisons with FAST/TEAMSComparisons with FAST/TEAMS

The FAST/TEAMS instrument is The FAST/TEAMS instrument is almost identical to CODIFalmost identical to CODIF

It has been operating for almost 9 It has been operating for almost 9 years - since August, 1996years - since August, 1996

Comparisons with FAST/TEAMS will Comparisons with FAST/TEAMS will give us some idea what to expect in give us some idea what to expect in the extended mission.the extended mission.

FAST/TEAMS EfficienciesFAST/TEAMS Efficiencies

After a significant increase in MCP After a significant increase in MCP voltage after the first year, the MCP voltage after the first year, the MCP voltage was kept constant for more voltage was kept constant for more than 3 years. Thus after 4 years, the than 3 years. Thus after 4 years, the efficiency had declined to 1% of the efficiency had declined to 1% of the original value.original value.

A series of increases in 2002 brought A series of increases in 2002 brought it up to a level where the instrument it up to a level where the instrument again took reasonable data.again took reasonable data.

After 8.5 years it is operating at After 8.5 years it is operating at about 6-10% of the original about 6-10% of the original efficiency.efficiency.

By occasionally increasing the By occasionally increasing the voltage, the efficiency is being kept voltage, the efficiency is being kept fairly constantfairly constant

The FAST MCP voltage has increased The FAST MCP voltage has increased 14% from 2.9 to 3.4 kV over the 14% from 2.9 to 3.4 kV over the mission. CODIF has so far increased mission. CODIF has so far increased 7%.7%.

Recent FAST Data (June 26, 2005)Recent FAST Data (June 26, 2005)

Teams Data All-Ion Data

H+

He+

O+

ConclusionsConclusions

Despite reduced efficiencies, TEAMS Despite reduced efficiencies, TEAMS continues to provide composition continues to provide composition information after almost 9 years.information after almost 9 years.

In addition, because of the coincidence In addition, because of the coincidence requirements, it continues to give reliable requirements, it continues to give reliable fluxes in the radiation belts, where the all-fluxes in the radiation belts, where the all-ion instruments cannot function.ion instruments cannot function.

We expect that CODIF on CLUSTER will We expect that CODIF on CLUSTER will similarly continue to perform for the similarly continue to perform for the duration of the extended mission.duration of the extended mission.