# Presentation: 154730

## SAMPEX PET

- (Proton/Electron Telescope)
- Light Isotope and Electron Data

- Mark Looper
- The Aerospace Corporation

## P1

- P2

- P3

- P4

- P5

- P6

- P7

- P8

- PET Electron Response

- (EGS4 Monte Carlo)

**Notes:**
Diagram of PET detector stack, with electron response for three channels (stopping in P2, P3, or P4-7).  From Spring 2004 AGU talk; reference: Looper, Mark D., J. B. Blake, Richard S. Selesnick, and Richard A. Mewaldt, “A Survey of Multi-MeV Electrons in Solar Energetic Particle Events Over a Complete Solar Cycle,” paper SH22A-01.

##  PET Analysis

-  6-second coincidence and livetime rates
-  20 PHA events per second (of all species/energies)
-  Use PHA events as representative sample of particle events triggering coincidence rates, applying cuts to isolate species (and, for ions, energy bins)
-  Use livetime rate to determine correction (not simple, and often not small) for deadtime, mostly P1
-  (Often, restrict to +/- 10 degrees from local j-perp to limit variation of flux across telescope aperture)
-  For electrons, convolution of candidate spectra with channel by channel response is needed to get energies

## Protons

- Electrons

**Notes:**
P1 vs. P2 event crossplot for PLO/ELO events (protons and electrons stopping in P2).  Also from Spring 2004 AGU talk.

## 3-detector H, He events

- Over poles, quiet times
- Fragmentation in window

**Notes:**
PHI (ions stopping in P3) ADC-channel crossplot showing H, He isotopes; note that rare isotopes (2H, 3H, 3He) are mostly formed by fragmentation in the Kapton window.
Nonetheless, this shows the isotope-resolution capability of the instrument, and we have detected real heavy hydrogen isotopes in the inner radiation belt.

## L < 1.2, 1992.5-1995

- Trapped H isotopes

**Notes:**
Figure 1 from 1996 COSPAR paper (L < 1.2, 3-detector events, cut on two mass estimates, through end of 1995).  Reference:  Looper, M. D., J. B. Blake, and R. A. Mewaldt, “Maps of Hydrogen Isotopes at Low Altitudes in the Inner Zone from SAMPEX Observations,” Advances in Space Research 21, 1679-1682 (1998).

## Protons & electrons stopping in P4-P7

**Notes:**
P2 vs. P3 pulse-height crossplot for protons (band at upper right, 65-86 MeV) and electrons (spot at lower left, about 10-20 MeV) stopping in P4 to P7.  Also from Spring 2004 AGU talk.

## Slide 8

**Notes:**
6-month plot of ELO (2-detector, about 2-6 MeV) electron countrate vs. L, over period of October/November 2003 activity.  Shows injection across slot, as well as outer-zone activity.  Also from Spring 2004 AGU talk.

## Slide 9

**Notes:**

6-month plot of PLO (2-detector, 19-29 MeV) proton countrate vs. L, for same period; shows SEP events, and dropout of inner-zone flux.  Also from Spring 2004 AGU talk.

## Slide 10

**Notes:**
6-month plot of EHI (stopping in P3, about 3-10 MeV) electron countrate vs. L, over same time as previous; also from Spring 2004 AGU talk.

## Slide 11

**Notes:**
6-month plot of RNG (stopping in P4 to P7, about 10-20 MeV) electron countrate vs. L, over same time as previous; also from Spring 2004 AGU talk.  Note new belt, a faint echo of March 1991 injection, appearing several months after SEP events (visible as band of high countrates extending to large L), presumably as initially highly-peaked pitch-angle distribution scatters down the field lines to SAMPEX.

## Near local j-perp

**Notes:**
Full-mission plot of RNG electrons vs. L, with cuts and averaging to avoid most artifacts and show countrate mirroring near the point of observation.  Also from Spring 2004 AGU talk.

## Near local j-perp

**Notes:**
Plot similar to previous one, for PLO (2-detector, about 19-29 MeV) protons.  Note solar-cycle modulation, and “fading” as SAMPEX orbit decays to lower altitudes in latter half of mission; note also uniqueness of flux dropout at October/November 2003 active period.

## Since SAMPEX doesn’t reach magnetic equator at most L, define pitch angle at minimum B observed at given L

**Notes:**
Plot of all proton events in lowest-energy bin (19-21 MeV), over entire mission, binned by B and L (actually invariant latitude); from Fall 2003 AGU talk, reference: Looper, Mark D., J. B. Blake, and Richard A. Mewaldt, “SAMPEX Observations of the Inner Radiation Belt Over a Complete Solar Cycle,” paper SM51E-01.  This shows where there is flux, but also is modulated by available telemetry in each region.  For example, the flux at this energy doesn’t drop out around invariant latitude of 30 degrees, but rather the telemetry allocation is shared there with a lot of much higher-energy protons.

## Protons

- Deuterons

- Average j-perp at max. altitude

**Notes:**
Mission-averaged flux of protons and deuterons mirroring at the maximum altitude reached by SAMPEX, as a function of energy and invariant latitude.  From Fall 2003 AGU talk.

## Average pitch-angle distribution at max. altitude

**Notes:**
Mission-average pitch-angle distribution for lowest-energy proton channel, projected to maximum altitude reached by SAMPEX, as a function of invariant latitude.  Also from Fall 2003 AGU talk.

## Normalized time variation at lowest proton energy

**Notes:**
Time variation over the mission in lowest proton energy channel, normalized to mission-averaged flux profile at each invariant latitude.  Note greatest solar-cycle variation amplitude at lowest invariant latitude; note also transient injection in late 2001 at high invariant latitude.  Also from Fall 2003 AGU talk.

## L = 1.150-1.155, 86-120 MeV, on equator

**Notes:**
Individual 6-second samples of 86-120 MeV proton countrate in one very tight B-L bin, over early part of mission, showing 3-month modulation.  Also from 1996 COSPAR paper (figure 2).

## Dashed line: scale height 75 km

**Notes:**
Data in previous plot normalized by 90-day average flux, and plotted against look direction (east to west).  Also from 1996 COSPAR paper (figure 3).  Remaining variation is entirely attributable to statistics--chi-squared relative to the dashed-line fit (for a flux scale height of 75 km in the magnetic equatorial plane) is less than the number of data points.

## Data (soon to be) available

-  Full 6-second time resolution hydrogen energy channels
-  6-second ELO and EHI (cleaned) electron rates
-  6-second ephemeris, pitch angle, attitude data
-  Quality flags (known artifacts, saturation, ...)
-  Data already at BIRA, soon to be updated
-  BIRA has improved on ephemeris alignment with rates
-  Documentation: quality, derivation, response functions, ...
-  Other SAMPEX data from all four instruments, including complete Master Data Files (if you’re brave enough!)