README.LEP
CAUTION: LEP count rate data may still contain background noise
depending on pitch angles.
The data less than 1000 cps may be unreliable.
Those less than 300 cps may be very unreliable.
Please ask MUKAI (ISAS, JAPAN) when using the LEP data of low
count rate as noted above.
One block of the LEP science data consists of 15 records of data,
each corresponding to 8-sec averaged count rates in 29 energy steps and
18 pitch angle ranges for electrons and ions, respectively. That is,
one block of data is represented by ICO(i,j,k), where i=1,29 (step No.),
j=1,18 (pitch angle every 10 degree), and k=1,15 (data No.). The block
NO (1 byte) is added at the head of each block. The elapsed time (in
seconds) for each record of data from the first data can be obtained by
delta-t = 120*NO + 8*(k-1). It is noted that the block NO may not be
continuous when a data gap exists.
ICO has a compressed form (2 bytes for each element), which can be
decomposed by SUBROUTINE DECOMP(ICO,CORATE), where ICO is an element of
ICO(i,j,k), and CORATE(2) are the de-compressed output for electrons (1)
and ions (2).
Conversion from the step NO (i) to the energy in eV can be done as
follows:
E(i) = 10.2 * exp(0.25466*i) for electrons, and
E(i) = 12.5 * exp(0.25466*i) for ions.
The number flux, J, can be obtained by J = CORATE/(G*E),
where G = 5.8E-5 for electrons and G = 2.3E-4 for ions, respectively.
It is noted that the unit of J is (cm^2 s sr eV)^(-1) when the above
equations are used for energy.
The phase space density can be obtained as follows.
For electrons; f = 1.616E-19 * (J/E)
For protons; f = 5.449E-13 * (J/E)
The unit of f is s^3 m^(-6), and the units of J and E are same as above.
For ions other than protons, f should be multiplied by (m_i/Q/m_p)^2.
SUBROUTINE DECOMP(ICO,CORATE)
************************************************************************
* THIS SUBROUTINE MAKES TRANSFORMATION OF THE COMPRESSED DATA *
* INTO THE RAW COUNT RATE. *
*----------------------------------------------------------------------*
* ICO: COMPRESSED COUNT RATE OF ELECTRONS AND IONS; I*2 (INPUT) *
* UPPER BYTE: ELECTRON DATA *
* LOWER BYTE: ION DATA *
* EACH BYTE = 0; DO NOT USE THIS DATA *
* = 1; CORATE LESS THAN 40 CPS. *
* > 1; INT( (ALOG10(CORATE)-1.6)*70. + 1 ) *
* = 255; MAY BE LARGER THAM 255 *
*----------------------------------------------------------------------*
* CORATE(2): DE-COMPRESSED COUNT RATE; R*4 *2 (OUTPUT) *
* I=1; ELECTRON DATA *
* I=2; ION DATA *
************************************************************************
INTEGER*2 ICO, ICOEI(2)
DIMENSION CORATE(2)
ICOEI(1) = ISHFT(ICO(I),-8)
ICOEI(2) = IAND(ICO(I),255)
DO 50 J=1,2
IF( ICOEI(J).EQ.0 ) THEN
CORATE = -9999.9
C THIS IS INSIGNIFICANT DATA.
ELSE
CORATE = 10.0**(1.6+(ICOEI(J)-1.0)/70.0)
ENDIF
50 CONTINUE
RETURN
END
************************************************************************