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                                                               

************************************************************************