**EPHIN/COSTEP**

**Level-2 Data Format Specification**

**for SOHO Archive**

Prepared by : Reinhold Müller-Mellin

Holger Boll

Carsten Scharmberg

April 2000

Contact address : Institut für Experimentelle und Angewandte Physik

Olshausenstr. 40, D-24118 Kiel, Germany

Reinhold Müller-Mellin

Phone: (49-431) 880 3227 Fax: (49-431) 85660

e-mail: mueller-mellin@kernphysik.uni-kiel.de

Holger Boll

Phone: (49-431) 880 4729 Fax: (49-431) 85660

e-mail: <boll@kernphysik.uni-kiel.de>

> Carsten Scharmberg

Phone: (49-431) 880 2516 Fax: (49-431) 85660

e-mail: <scharmberg@kernphysik.uni-kiel.de>

**1. Data Product**

The EPHIN instrument (Electron Proton Helium INstrument) forms part of
the COSTEP experiment (COmprehensive SupraThermal and Energetic Particle
Analyser) within the CEPAC collaboration on bord of the SOHO spacecraft
(SOlar and Heliospheric Observatory). For a detailed description of the
SOHO mission and the COSTEP experiment see *Solar Physics*, **162**,
1995.

The EPHIN instrument produces scientific data at a constant rate of 172
bit/s or 15 megabit per day and housekeeping data at a rate of 0.25
megabit per day (Level Zero data). This data set is processed at the
University of Kiel in two steps yielding Level 1 and Level 2 products.
The Level 2 data set is organized in files per day, primarily counting
rate information (\~ 0.36 megabyte per day) and pulse height analysis
information (\~ 15 megabyte per day) together with their detached header
files. Furthermore a correction file (\~0.16 megabyte per day) is
included which can be used to correct the counting rates for
instrumental effects (e.g. gamma ray and neutron produced background,
contamination of one particle species by the other) and to separate
isotopes. The distribution medium is CD-ROM. Together with the
LION/COSTEP data set one CD-ROM is produced per month. AAREADME and
CAVEAT text files are included which can be read by WORD (Text only) or
other suitable editors.

**Data Files:**

  ------------------------------ ----------------------------------------
  **File Contents**              **Name Convention**

  EPHIN counting rates           EPxyydoy.RL2; 1995 - 1999: x=H since
                                 2000: x=I

  EPHIN pulse height analysis    EPxyydoy.PL2; 1995 - 1999: x=H since
  (PHA)                          2000: x=I

  EPHIN rate correction          EPxyydoy.KOR; 1995 - 1999: x=H since
                                 2000: x=I
  ------------------------------ ----------------------------------------

**Detached Header Files:**

  ------------------------------ ----------------------------------------
  **File Contents**              **Name Convention**

  File header for rate data file EPxyydoy.MR2; 1995 - 1999: x=H since
                                 2000: x=I

  File header for PHA data file  EPxyydoy.MP2; 1995 - 1999: x=H since
                                 2000: x=I
  ------------------------------ ----------------------------------------

-   Counting rates are given as intensities in units of counts/cm^2^ s
    sr MeV, a subset of counting rates is given as counting results per
    accumulation interval of 59.953 seconds. The factors which were used
    to convert counting results into intensities are given in chapter 5.

-   Pulse height words are given as energy deposits in units of MeV. The
    conversion factors which were used to convert ADC value of a pulse
    height into MeV are given in chapter 6.

-   Rate correction data are given as counts, from which the correction
    factor can be derived.

-   Time resolution for all 3 data sets is 1 minute (exact accumulation
    period is 59.953 seconds).

    **2. Data Format Description**

    **2.1 Counting rates file: EPxyydoy.RL2**

+----+---------------+---------------+---------------+---------------+
| ** | **Label:**    | **Data Type** | **Data        | **Units**     |
| It |               |               | Contents**    |               |
| em |               |               |               |               |
| ** |               |               |               |               |
+----+---------------+---------------+---------------+---------------+
| 1  | PB5 Year      | integer       | year          | year 4 digits |
|    |               |               |               |               |
| 2  | DOY           | integer       | day of year   | day 1 \...    |
|    |               |               |               | 366           |
| 3  | MS            | integer       | milliseconds  |               |
|    |               |               | of day        | ms 0 \...     |
|    |               |               |               | 86,400,000    |
+----+---------------+---------------+---------------+---------------+
| 4  | S/C Epoch     | float         | ms since year | ms 14 digits  |
|    |               | (double)      | 0             |               |
+----+---------------+---------------+---------------+---------------+
| 5  | Status Word   | Integer       | bits 0 to 31  | binary        |
|    | part 1        |               |               |               |
| 6  |               | Integer       | bits 32 to 39 | binary        |
|    | Status Word   |               |               |               |
|    | part 2        |               | see chapter 3 |               |
+----+---------------+---------------+---------------+---------------+
| 7  | E150          | float (E-Fmt) | intensity     | /cm^2^ s sr   |
|    |               |               |               | MeV           |
| 8  | E300          | float (E-Fmt) | intensity     |               |
|    |               |               |               | /cm^2^ s sr   |
| 9  | E1300         | float (E-Fmt) | intensity     | MeV           |
|    |               |               |               |               |
| 10 | E3000         | float (E-Fmt) | intensity     | /cm^2^ s sr   |
|    |               |               |               | MeV           |
| 11 | P4            | float (E-Fmt) | intensity     |               |
|    |               |               |               | /cm^2^ s sr   |
| 12 | P8            | float (E-Fmt) | intensity     | MeV           |
|    |               |               |               |               |
| 13 | P25           | float (E-Fmt) | intensity     | /cm^2^ s sr   |
|    |               |               |               | MeV           |
| 14 | P41           | float (E-Fmt) | intensity     |               |
|    |               |               |               | /cm^2^ s sr   |
|    |               |               |               | MeV           |
|    |               |               |               |               |
|    |               |               |               | /cm^2^ s sr   |
|    |               |               |               | MeV           |
|    |               |               |               |               |
|    |               |               |               | /cm^2^ s sr   |
|    |               |               |               | MeV           |
+----+---------------+---------------+---------------+---------------+

**Counting rates file: EPxyydoy.RL2 (continued)**

+----+---------------+---------------+---------------+---------------+
| ** | **Label**     | **Data Type** | **Data        | **Units**     |
| It |               |               | Contents**    |               |
| em |               |               |               |               |
| ** |               |               |               |               |
+----+---------------+---------------+---------------+---------------+
| 15 | H4            | float (E-Fmt) | intensity     | /cm^2^ s sr   |
|    |               |               |               | MeV/n         |
| 16 | H8            | float (E-Fmt) | intensity     |               |
|    |               |               |               | /cm^2^ s sr   |
| 17 | H25           | float (E-Fmt) | intensity     | MeV/n         |
|    |               |               |               |               |
| 18 | H41           | float (E-Fmt) | intensity     | /cm^2^ s sr   |
|    |               |               |               | MeV/n         |
| 19 | INT           | float (E-Fmt) | intensity     |               |
|    |               |               |               | /cm^2^ s sr   |
|    |               |               |               | MeV/n         |
|    |               |               |               |               |
|    |               |               |               | /cm^2^ s sr   |
+----+---------------+---------------+---------------+---------------+
| 20 | P4 GM         | integer       | particle      | counts        |
|    |               |               | count         |               |
| 21 | P4 GR         | integer       |               | counts        |
|    |               |               | particle      |               |
| 22 | P4 S          | integer       | count         | counts        |
|    |               |               |               |               |
|    |               |               | particle      |               |
|    |               |               | count         |               |
+----+---------------+---------------+---------------+---------------+
| 23 | P8 GM         | integer       | particle      | counts        |
|    |               |               | count         |               |
| 24 | P8 GR         | integer       |               | counts        |
|    |               |               | particle      |               |
| 25 | P8 S          | integer       | count         | counts        |
|    |               |               |               |               |
|    |               |               | particle      |               |
|    |               |               | count         |               |
+----+---------------+---------------+---------------+---------------+
| 26 | P25 GM        | integer       | particle      | counts        |
|    |               |               | count         |               |
| 27 | P25 GR        | integer       |               | counts        |
|    |               |               | particle      |               |
| 28 | P25 S         | integer       | count         | counts        |
|    |               |               |               |               |
|    |               |               | particle      |               |
|    |               |               | count         |               |
+----+---------------+---------------+---------------+---------------+
| 29 | P41 GM        | integer       | particle      | counts        |
|    |               |               | count         |               |
| 30 | P41 GR        | integer       |               | counts        |
|    |               |               | particle      |               |
| 31 | P41 S         | integer       | count         | counts        |
|    |               |               |               |               |
|    |               |               | particle      |               |
|    |               |               | count         |               |
+----+---------------+---------------+---------------+---------------+
| 32 | H4 GM         | integer       | particle      | counts        |
|    |               |               | count         |               |
| 33 | H4 GR         | integer       |               | counts        |
|    |               |               | particle      |               |
| 34 | H4 S1         | integer       | count         | counts        |
|    |               |               |               |               |
| 35 | H4 S23        | integer       | particle      | counts        |
|    |               |               | count         |               |
|    |               |               |               |               |
|    |               |               | particle      |               |
|    |               |               | count         |               |
+----+---------------+---------------+---------------+---------------+
| 36 | H8 GM         | integer       | particle      | counts        |
|    |               |               | count         |               |
| 37 | H8 GR         | integer       |               | counts        |
|    |               |               | particle      |               |
| 38 | H8 S1         | integer       | count         | counts        |
|    |               |               |               |               |
| 39 | H8 S23        | integer       | particle      | counts        |
|    |               |               | count         |               |
|    |               |               |               |               |
|    |               |               | particle      |               |
|    |               |               | count         |               |
+----+---------------+---------------+---------------+---------------+
| 40 | H25 GM        | integer       | particle      | counts        |
|    |               |               | count         |               |
| 41 | H25 GR        | integer       |               | counts        |
|    |               |               | particle      |               |
| 42 | H25 S1        | integer       | count         | counts        |
|    |               |               |               |               |
| 43 | H25 S23       | integer       | particle      | counts        |
|    |               |               | count         |               |
|    |               |               |               |               |
|    |               |               | particle      |               |
|    |               |               | count         |               |
+----+---------------+---------------+---------------+---------------+
| 44 | H41 GM        | integer       | particle      | counts        |
|    |               |               | count         |               |
| 45 | H41 GR        | integer       |               | counts        |
|    |               |               | particle      |               |
| 46 | H41 S1        | integer       | count         | counts        |
|    |               |               |               |               |
| 47 | H41 S23       | integer       | particle      | counts        |
|    |               |               | count         |               |
|    |               |               |               |               |
|    |               |               | particle      |               |
|    |               |               | count         |               |
+----+---------------+---------------+---------------+---------------+
| 48 | Status Flag   | integer       | see chapter 4 | binary        |
+----+---------------+---------------+---------------+---------------+
| 49 | Spare         |               |               |               |
|    |               |               |               |               |
| 50 | Spare         |               |               |               |
|    |               |               |               |               |
| 51 | Spare         |               |               |               |
+----+---------------+---------------+---------------+---------------+

GM = Particles incident parallel to sensor axis, passing through both
center segments: A0 and B0

(0 \... 21)

GR = Particles incident parallel to sensor axis, passing through
corresponding ring segments: A1 and B1 or \... or A5 and B5 (0 \... 28)

S1 = Particles incident at oblique angle through one center segment and
one ring segment: A0 and

B1 or \... or A5 and B0 (0 \... 34)

S23 = Particles incident at oblique angle through ring segments: A1 and
B2 \... or A1 and B3

(0 \... 42)

**2.2 PHA file: EPxyydoy.PL2**

+-----+---------------+---------------+---------------+---------------+
| **  | **Label**     | **Data Type** | **Data        | **U           |
| Ite |               |               | Contents**    | nits/Values** |
| m** |               |               |               |               |
+-----+---------------+---------------+---------------+---------------+
| 1   | S/C Epoch     | float         | ms since year | ms 14 digits  |
|     |               | (double)      | 0             |               |
+-----+---------------+---------------+---------------+---------------+
| 2   | Co            | integer       | coincidence   | 0 \... 12     |
|     |               |               | type          |               |
+-----+---------------+---------------+---------------+---------------+
| 3   | Aseg          | integer       | segment det.  | 0 \... 5      |
|     |               |               | A             |               |
| 4   | Bseg          | integer       |               | 0 \... 5      |
|     |               |               | segment det.  |               |
| 5   | Pri           | integer       | B             | 0 or 1        |
|     |               |               |               |               |
|     |               |               | priority flag |               |
+-----+---------------+---------------+---------------+---------------+
| 6   | PHA_A         | float (F-Fmt) | energy loss   | MeV           |
|     |               |               | in det. A     |               |
+-----+---------------+---------------+---------------+---------------+
| 7   | PHA_B         | float (F-Fmt) | energy loss   | MeV           |
|     |               |               | in det. B     |               |
+-----+---------------+---------------+---------------+---------------+
| 8   | PHA_C         | float (F-Fmt) | energy loss   | MeV           |
|     |               |               | in det. C     |               |
+-----+---------------+---------------+---------------+---------------+
| 9   | PHA_D         | float (F-Fmt) | energy loss   | MeV           |
|     |               |               | in det. D     |               |
+-----+---------------+---------------+---------------+---------------+
| 10  | PHA_E         | float (F-Fmt) | energy loss   | MeV           |
|     |               |               | in det. E     |               |
+-----+---------------+---------------+---------------+---------------+
| 11  | E_tot         | float (F-Fmt) | total energy  | MeV           |
|     |               |               | loss          |               |
+-----+---------------+---------------+---------------+---------------+
| 12  | spare         |               |               |               |
|     |               |               |               |               |
| 13  | spare         |               |               |               |
|     |               |               |               |               |
| 14  | spare         |               |               |               |
|     |               |               |               |               |
| 15  | spare         |               |               |               |
+-----+---------------+---------------+---------------+---------------+

  ---------- ------ ------ ------- ------- ---- ---- ----- ----- ---- ---- ----- ----- -----
  Coincid.   0      1      2       3       4    5    6     7     8    9    10    11    12
  type                                                                                 

  Channel    E150   E300   E1300   E3000   P4   P8   P25   P41   H4   H8   H25   H41   INT
  ---------- ------ ------ ------- ------- ---- ---- ----- ----- ---- ---- ----- ----- -----

**2.3 Rate correction file: EPxyydoy.KOR**

+---+----------------------------------------+---------+--------------+
| * | **Data contents**                      | **Data  | **Units**    |
| * |                                        | type**  |              |
| I |                                        |         |              |
| t |                                        |         |              |
| e |                                        |         |              |
| m |                                        |         |              |
| * |                                        |         |              |
| * |                                        |         |              |
+---+----------------------------------------+---------+--------------+
| 1 | year                                   | integer | year: 4      |
|   |                                        |         | digits       |
| 2 | day of year                            | integer |              |
|   |                                        |         | day:         |
| 3 | ms of day                              | integer | 1\...366     |
|   |                                        |         |              |
|   |                                        |         | ms:          |
|   |                                        |         | 0\.          |
|   |                                        |         | ..86,400,000 |
+---+----------------------------------------+---------+--------------+
| 4 | ms since year 0                        | float   | ms: 14       |
|   |                                        | (       | digits       |
|   |                                        | double) |              |
+---+----------------------------------------+---------+--------------+
| 5 | P4                                     | integer | counts       |
|   |                                        |         |              |
| 6 | Ptota total \# of particles in P4 PHA, | integer | counts       |
|   | arbitrary incidence                    |         |              |
| 7 |                                        | integer | counts       |
|   | p+d \# particles in proton & deuterium |         |              |
| 8 | box, arb. incidence                    | integer | counts       |
|   |                                        |         |              |
| 9 | Ptotp total \# of particles in P4 PHA, | integer | counts       |
|   | parallel incidence                     |         |              |
|   |                                        |         |              |
|   | p \# of particles in proton box,       |         |              |
|   | parallel incidence                     |         |              |
|   |                                        |         |              |
|   | d \# of particles in deuterim box,     |         |              |
|   | parallel incidence                     |         |              |
+---+----------------------------------------+---------+--------------+
| 1 | P8                                     | integer | counts       |
| 0 |                                        |         |              |
|   | Ptota total \# of particles in P8 PHA, | integer | counts       |
| 1 | arbitrary incidence                    |         |              |
| 1 |                                        | integer | counts       |
|   | p+d \# particles in proton & deuterium |         |              |
| 1 | box, arb. incidence                    | integer | counts       |
| 2 |                                        |         |              |
|   | Ptotp total \# of particles in P8 PHA, | integer | counts       |
| 1 | parallel incidence                     |         |              |
| 3 |                                        |         |              |
|   | p \# of particles in proton box,       |         |              |
| 1 | parallel incidence                     |         |              |
| 4 |                                        |         |              |
|   | d \# of particles in deuterim box,     |         |              |
|   | parallel incidence                     |         |              |
+---+----------------------------------------+---------+--------------+
| 1 | P25                                    | integer | counts       |
| 5 |                                        |         |              |
|   | Ptota total \# of particles in P25     | integer | counts       |
| 1 | PHA, arbitrary incidence               |         |              |
| 6 |                                        | integer | counts       |
|   | p+d \# particles in proton & deuterium |         |              |
| 1 | box, arb. incidence                    | integer | counts       |
| 7 |                                        |         |              |
|   | Ptotp total \# of particles in P25     | integer | counts       |
| 1 | PHA, parallel incidence                |         |              |
| 8 |                                        |         |              |
|   | p \# of particles in proton box,       |         |              |
| 1 | parallel incidence                     |         |              |
| 9 |                                        |         |              |
|   | d \# of particles in deuterim box,     |         |              |
|   | parallel incidence                     |         |              |
+---+----------------------------------------+---------+--------------+
| 2 | P41                                    | integer | counts       |
| 0 |                                        |         |              |
|   | Ptota total \# of particles in P41     | integer | counts       |
| 2 | PHA, arbitrary incidence               |         |              |
| 1 |                                        | integer | counts       |
|   | p+d \# particles in proton & deuterium |         |              |
| 2 | box, arb. incidence                    | integer | counts       |
| 2 |                                        |         |              |
|   | Ptotp total \# of particles in P41     | integer | counts       |
| 2 | PHA, parallel incidence                |         |              |
| 3 |                                        |         |              |
|   | p \# of particles in proton box,       |         |              |
| 2 | parallel incidence                     |         |              |
| 4 |                                        |         |              |
|   | d \# of particles in deuterim box,     |         |              |
|   | parallel incidence                     |         |              |
+---+----------------------------------------+---------+--------------+
| 2 | H4                                     | integer | counts       |
| 5 |                                        |         |              |
|   | Ptota total \# of particles in H4 PHA, | integer | counts       |
| 2 | arbitrary incidence                    |         |              |
| 6 |                                        | integer | counts       |
|   | ^3^He + ^4^He \# particles in ^3^He +  |         |              |
| 2 | ^4^He box, arb.incidence               | integer | counts       |
| 7 |                                        |         |              |
|   | Ptotp total \# of particles in H4 PHA, | integer | counts       |
| 2 | parallel incidence                     |         |              |
| 8 |                                        |         |              |
|   | ^3^He \# of particles in ^3^He box,    |         |              |
| 2 | parallel incidence                     |         |              |
| 9 |                                        |         |              |
|   | ^4^He \# of particles in ^4^He box,    |         |              |
|   | parallel incidence                     |         |              |
+---+----------------------------------------+---------+--------------+
| 3 | H8                                     | integer | counts       |
| 0 |                                        |         |              |
|   | Ptota total \# of particles in H8 PHA, | integer | counts       |
| 3 | arbitrary incidence                    |         |              |
| 1 |                                        | integer | counts       |
|   | ^3^He + ^4^He \# particles in ^3^He +  |         |              |
| 3 | ^4^He box, arb.incidence               | integer | counts       |
| 2 |                                        |         |              |
|   | Ptotp total \# of particles in H8 PHA, | integer | counts       |
| 3 | parallel incidence                     |         |              |
| 3 |                                        |         |              |
|   | ^3^He \# of particles in ^3^He box,    |         |              |
| 3 | parallel incidence                     |         |              |
| 4 |                                        |         |              |
|   | ^4^He \# of particles in ^4^He box,    |         |              |
|   | parallel incidence                     |         |              |
+---+----------------------------------------+---------+--------------+
| 3 | H25                                    | integer | counts       |
| 5 |                                        |         |              |
|   | Ptota total \# of particles in H25     | integer | counts       |
| 3 | PHA, arbitrary incidence               |         |              |
| 6 |                                        | integer | counts       |
|   | ^3^He + ^4^He \# particles in ^3^He +  |         |              |
| 3 | ^4^He box, arb.incidence               | integer | counts       |
| 7 |                                        |         |              |
|   | Ptotp total \# of particles in H25     | integer | counts       |
| 3 | PHA, parallel incidence                |         |              |
| 8 |                                        |         |              |
|   | ^3^He \# of particles in ^3^He box,    |         |              |
| 3 | parallel incidence                     |         |              |
| 9 |                                        |         |              |
|   | ^4^He \# of particles in ^4^He box,    |         |              |
|   | parallel incidence                     |         |              |
+---+----------------------------------------+---------+--------------+
| 4 | H41                                    | integer | counts       |
| 0 |                                        |         |              |
|   | Ptota total \# of particles in H41     | integer | counts       |
| 4 | PHA, arbitrary incidence               |         |              |
| 1 |                                        | integer | counts       |
|   | ^3^He + ^4^He \# particles in ^3^He +  |         |              |
| 4 | ^4^He box, arb.incidence               | integer | counts       |
| 2 |                                        |         |              |
|   | Ptotp total \# of particles in H41     | integer | counts       |
| 4 | PHA, parallel incidence                |         |              |
| 3 |                                        |         |              |
|   | ^3^He \# of particles in ^3^He box,    |         |              |
| 4 | parallel incidence                     |         |              |
| 4 |                                        |         |              |
|   | ^4^He \# of particles in ^4^He box,    |         |              |
|   | parallel incidence                     |         |              |
+---+----------------------------------------+---------+--------------+

Energetic particles can undergo several processes in the EPHIN
telescope, which lead to inaccurate particle classification: e.g.
electrons can be scattered by large angles, reducing their penetration
depth in the detector stack and thus mimicking nuclei, nuclei can pass
through insensitive matter like detector mounts, depositing less
observable energy, or suffer from nuclear interaction in the silicon
detector. This is to a large degree unavoidable, but can be corrected to
some degree by pulse height analysis. Using ground data from accelerator
calibration and flight data from the first 8 months of SOHO operation,
calibration curves for the various nuclei species were established.
Boxes around these curves allow elemental and isotopic separation for
protons, deuterium, helium-3 and helium-4. Restriction to only particles
incident parallel to the optical axis of the telescope decreases the
path length variation, thereby increasing the isotopic resolution at the
expense of statistical accuracy. To improve on statistics, averaging
over longer time periods may be carried out. Owing to multiple
scattering there is no easy correction available for electron channels.

**How to correct the counting rates:**

1\. divide the number of PHA counts in the box by the total number of
PHA counts

2\. apply this correction factor to the associated counting rate

**Example for arbitrary incidence:**

item 6 of EPxyydoy.KOR

P4 ~corrected~ = P4 ~uncorrected~ ( = item 11 of EPxyydoy.RL2) •

item 5 of EPxyydoy.KOR

**Example for parallel incidence:**

item 20 + item 21 of EPxyydoy.RL2 item 8 + item 9 of EPxyydoy.KOR

P4 ~corrected~ = •

59.953 • 1.02 • 3.5 item 7 of EPxyydoy.KOR

Note: for parallel incidence the counting results must be converted into
intensities. The geometric factor for the sum of six segments
(P4GM+P4GR) is about 5 % less than 6 times the geometric factor for the
center segments (Ring A/B OFF, see chapter 5).

**How to average corrected fluxes over n minutes:**

1 n

Average = ( counting rate • correction factor )

n i = 1

**2.4 Header for Rate Data File: EPxyydoy.MR2**

Example:

University of Kiel, Extraterrestrial Physics Group

PI: Horst Kunow

Program: GENSCIL2, Author: Holger Boll, Jan-97

Program_Version: 1.0

Data_Version: V01

Project: SOHO-COSTEP

Instrument: EPHIN

Data_Type: Rates

Data_File_Name:EPH97001.RL2

Data_File_Type: ASCII

Generation_Date: Tue Feb 18 16:48:43 1997

Data_Period_Start: 1997-01-01 00:01:10

Data_Period_End : 1997-01-01 23:59:02

Parameter_File_Name: EPH_IFAC.PRO

**2.5 Header for PHA Data File: EPxyydoy.MP2**

Example:

University of Kiel, Extraterrestrial Physics Group

PI: Horst Kunow

Program: GENPHAL2, Author: Holger Boll, Jan-97

Program_Version: 1.0

Data_Version: V01

Project: SOHO-COSTEP

Instrument: EPHIN

Data_Type: Pulse Height Analysis

Data_File_Name: EPH97001.PL2

Data_File_Type: ASCII

Generation_Date: Thu Feb 13 14:15:58 1997

Data_Period_Start: 1997-01-01 00:01:10

Data_Period_End : 1997-01-01 23:59:02

Parame ter_File_Name: PHA_BIN_ENERG.PRO

**3. EPHIN Status Word**

The EPHIN status word in words 5 and 6 of the counting rate file is
implemented by hardware in the onboard EPHIN electronics and telemetered
to ground. Its unrestricted use requires detailed knowledge of the EPHIN
hardware. For data evaluation by scientists less familiar with the
hardware, an EPHIN status flag in word 48 of the counting rate file has
been implemented by software (see chapter 4).

  ----------- -------------- --------------- --------- -------- ------- ------ --------- ------- --------- -------------
  **Label**   **Bit**        **EPHIN Status                                                                
                             Information**                                                                 

              **Position**   **MSB**                                                             **LSB**   **Comment**

  Status part 31 -- 24       N/U             FMB       FMB5     FMB4    FMB3   FMB2      FMB1    FMB0      Fail. mode
  1                                                                                                        

  default                    0               1         1        1       1      1         1       1         Det. B

  Status part 23 -- 16       Ring            FMA       FMA5     FMA4    FMA3   FMA2      FMA1    FMA0      Fail. mode
  1                                                                                                        

  default                    0               1         1        1       1      1         1       1         Det. A

  Status part 15 -- 8        N/U             Reset     Wdog     PROM    SRAM   RAM       Dwnld   Upld      CPU status
  1                                                                                                        

  default                    0               0         0        1       1      1         0       0         

  Status part 7 -- 0         Op Mode                   SIO Fr   SIO Ovr SIO    Minute                      mode, error,
  1                                                                     Par    Counter                     

  default                    0               1         0        0       0      X         X       X         frame count

  Status part 31 -- 8        N/U                                                                           
  2                                                                                                        

  default                    0                                                                             

  Status part 7 -- 0         Det.G           Det.A-F   An.Pow   FMG     FMF    FME       FMD     FMC       Power and
  2                                                                                                        

  default                    1               1         1        1       1      1         1       1         Fail. mode
  ----------- -------------- --------------- --------- -------- ------- ------ --------- ------- --------- -------------

N/U = not used SIO Fr, Ovr, Par = Serial Input Output framing error,
overrun error, parity error

X = don't care Wdog = watchdog event

Op mode 00 = standby, 01 = nominal operation, 10 = calibration, 11 = not
allowed

**4. EPHIN Status Flag**

The EPHIN status flag shall facilitate the use of the EPHIN data set
without detailed knowledge of the EPHIN hardware status bits and their
effects. The status flag is generated by ground software. It is located
in word 48 of the counting rate file. The contents of the status flag is
a decimal code which results from the summation of the flag bit values.

  ----------- -----------------------------------------------------------
  **Flag Bit  **Remarks**
  Value**     

  0           Nominal observation, i.e. High Voltage ON, no failure mode,
              ring segment switching disabled

  1           Failure mode E

  2           Ring A/B OFF

  4           E patch uploaded

  8           Commissioning

  16          Standby or maintenance, i.e. High Voltage OFF

  32          Calibration, i.e. test mode

  64          Ring segment switching enabled

  128         TBD
  ----------- -----------------------------------------------------------

**4.1 Status Flag History**

A status flag history is given from first switch-on in December 1995
until February 1998. The status flag is valid from the time indicated
until a new status flag is listed. An updated list of the status flag is
included on the Level 2 distribution medium (see CAVEAT.TXT).

  ---------- ----------- --------- ---------- ------------ ---------- -------------------------------
  **Year**   **Month**   **Day**   **Hour**   **Minute**   **Status   **Change**
                                                           Flag**     

  1995       12          07        17         28           16         EPHIN ON (standby or
                                                                      maintenance)

  1995       12          07        17         35           0          Nominal observation

  1995       12          09        17         03           8          Commissioning

  1995       12          10        05         15           0          Nominal observation

  1996       10          31        14         47           1          Failure mode E

  1996       12          12        16         42           3          Ring A/B OFF (for check-out
                                                                      only)

  1996       12          18        14         45           1          Ring A/B ON (back to normal)

  1997       02          15        10         25           -1         EPHIN OFF (no data)

  1997       02          16        16         37           16         EPHIN ON (standby or
                                                                      maintenance)

  1997       02          16        16         45           0          Nominal observation

  1997       02          19        14         57           1          Failure mode E

  1997       03          13        14         41           5          Upload E patch (salvage PHA_E)

  1997       04          23        16         19           37         Calibration

  1997       04          23        16         28           5          End calibration

  1997       08          22        13         10           5          Upload histogram patch
                                                                      (parallel incidence)

  1997       10          10        14         39           69         Enable ring segment switching
  ---------- ----------- --------- ---------- ------------ ---------- -------------------------------

Note:

-   The code -1 (no data) is dummy. It will not show up in L2 data
    records as it is only introduced for the purpose of machine reading
    above table.

-   The first table or software upload after EPHIN ON will set bit 2^2^
    (value 4). It can only be cleared by power cycling or by a reset
    command. A second upload will not be recognizable as a status change
    (see e.g. histogram patch on 22-AUG-97).

**4.2 Example**

In order to select data which are taken with EPHIN in observation mode
(not always nominal !) the flag shall have the following contents:

+--------+--------+--------+------------------------------------------+
| **S    | **     | **     | **Remarks**                              |
| tart** | Stop** | Status |                                          |
|        |        | Flag** |                                          |
+--------+--------+--------+------------------------------------------+
| 07-    | 09-    | 0      | Nominal observation                      |
| DEC-95 | DEC-95 |        |                                          |
+--------+--------+--------+------------------------------------------+
| 10-    | 31-    | 0      | Nominal observation                      |
| DEC-95 | OCT-96 |        |                                          |
+--------+--------+--------+------------------------------------------+
| 31-    | 12-    | 1      | Failure mode E                           |
| OCT-96 | DEC-96 |        |                                          |
|        |        |        | Rates: E3000, P41, H41 show zero counts, |
|        |        |        | corresponding events                     |
|        |        |        |                                          |
|        |        |        | are counted together with E1300, P25,    |
|        |        |        | H25, hence use                           |
|        |        |        |                                          |
|        |        |        | larger energy window.                    |
|        |        |        |                                          |
|        |        |        | PHA: no PHA words for E3000, P41, H41,   |
|        |        |        | corresponding events                     |
|        |        |        |                                          |
|        |        |        | are pulse height analyzed as E1300, P25, |
|        |        |        | H25, pulse                               |
|        |        |        |                                          |
|        |        |        | heights for E (PHA_E) are lost.          |
+--------+--------+--------+------------------------------------------+
| 12-    | 18-    | 3      | Failure mode E with ring A/B OFF         |
| DEC-96 | DEC-96 |        |                                          |
|        |        |        | Rates: as in failure mode E above but    |
|        |        |        | use small geometry factor                |
|        |        |        |                                          |
|        |        |        | PHA: as in failure mode E above          |
+--------+--------+--------+------------------------------------------+
| 18-    | 19-    | 1      | Failure mode E (see above)               |
| DEC-96 | FEB-97 |        |                                          |
+--------+--------+--------+------------------------------------------+
| 19-    | 10-    | 5      | Failure mode E with upload of E-patch,   |
| FEB-97 | OCT-97 |        | i.e. recovery of PHA_E                   |
|        |        |        |                                          |
|        |        |        | Rates: as in failure mode E above        |
|        |        |        |                                          |
|        |        |        | PHA: no PHA words for E1300, P25, H25    |
|        |        |        | events corresponding                     |
|        |        |        |                                          |
|        |        |        | events are pulse height analyzed as      |
|        |        |        | E3000, P41, H41.                         |
|        |        |        |                                          |
|        |        |        | PHA_E = zero for true E1300, P25, H25    |
|        |        |        | events                                   |
|        |        |        |                                          |
|        |        |        | PHA_E \> zero for true E3000, P41, H41   |
|        |        |        | events.                                  |
+--------+--------+--------+------------------------------------------+
| 10-    | \>     | 69     | Failure mode E with upload of E-patch    |
| OCT-97 | FEB-98 |        | and automatic ring segment switching     |
|        |        |        | enabled                                  |
|        |        |        |                                          |
|        |        |        | Irregular status changes may occur       |
|        |        |        | automatically: \"RING A/B OFF\", i.e.    |
|        |        |        | bit value 2 is added (flag =71). This    |
|        |        |        | status change is event driven, it        |
|        |        |        | switches to the low geometric factor     |
|        |        |        | during high fluxes. On detection of low  |
|        |        |        | fluxes, the ring segments are switched   |
|        |        |        | back on again. The occurrence is not     |
|        |        |        | recorded in this table.                  |
+--------+--------+--------+------------------------------------------+

**5. EPHIN Intensity Factors**

Part of the Level-2 counting rates are already converted into
intensities \[counts/(cm^2^ s sr MeV/n)\] by dividing the counting rates
\[counts/s\] through the intensity factor:

**Intensity Factor = Geometry Factor Energy Window \[cm^2^ sr MeV/n\]**

The factors vary with observation modes of EPHIN. The following
observation modes with influence on the intensity factor have been in
use during the SOHO prime mission:

  ------------------ ----------------------------------------------------
  **Observation      **Description**
  Mode**             

  nominal mode       High voltage on, all detectors logically on

  failure mode E     High voltage on, detector E logically off

  ring A/B off       High voltage on, segments A1 ... A5 and B1 ... B5
                     logically off and respective preamplifier power off
  ------------------ ----------------------------------------------------

**Geometry Factor: units: cm^2^ sr**

  ------------- ------------ --------- -------- -----------------------------
  **Geometry                                    
  factor:                                       
  nominal                                       
  observation                                   
  mode**                                        

  0.25          1.78         2.01      1.58     E150, E300, E1300, E3000

  5.14          5.14         4.77      3.8      P4, P8, P25, P41

  5.14          5.14         4.77      3.8      H4, H8, H25, H41

  6.85                                          INT
  ------------- ------------ --------- -------- -----------------------------

  ------------ ------------ --------- -------- -----------------------------
  **Geometry                                   
  factor:                                      
  failure mode                                 
  E**                                          

  0.25         1.78         1.8       1\.      E150, E300, E1300, E3000

  5.14         5.14         4.29      1\.      P4, P8, P25, P41

  5.14         5.14         4.29      1\.      H4, H8, H25, H41

  7.84                                         INT
  ------------ ------------ --------- -------- -----------------------------

  ------------ ------------ --------- -------- -----------------------------
  **Geometry                                   
  factor: ring                                 
  A/B off and                                  
  failure mode                                 
  E**                                          

  0.01         0.14         0.11      1\.      E150, E300, E1300, E3000

  0.18         0.18         0.18      1\.      P4, P8, P25, P41

  0.18         0.18         0.18      1\.      H4, H8, H25, H41

  0.36                                         INT
  ------------ ------------ --------- -------- -----------------------------

Note: The combination ring A/B off without failure mode E will probably
never occur.

**Energy Window: units: MeV or MeV/n**

  ------------- ------------ --------- -------- -----------------------------
  **Energy                                      
  window:                                       
  nominal                                       
  observation                                   
  mode**                                        

  0.45          2.3          3.6       5.2      E150, E300, E1300, E3000

  3.5           17.2         16\.      12\.     P4, P8, P25, P41

  3.5           17.2         16\.      12\.     H4, H8, H25, H41

  1\.                                           INT
  ------------- ------------ --------- -------- -----------------------------

  ---------- ------------ --------- -------- -----------------------------
  **Energy                                   
  window:                                    
  failure                                    
  mode E**                                   

  0.45       2.3          7.4       1\.      E150, E300, E1300, E3000

  3.5        17.2         28\.      1\.      P4, P8, P25, P41

  3.5        17.2         28\.      1\.      H4, H8, H25, H41

  1\.                                        INT
  ---------- ------------ --------- -------- -----------------------------

Note:

-   No energy window is given for the integral counter INT. The geometry
    factor given is twice the forward incident factor assuming an
    idealized response for forward and backward incident particles. The
    actual factor is somewhat lower due to absorption in the spacecraft
    matter.

-   Switching ring segments off does not change the energy window

**6. EPHIN PHA conversion factors**

The Level 2 data in the PHA files are given in units of MeV. The
following conversion factors were used to convert the telemetered
channel number TLM~i~, i.e. the analog-to-digital converter result of a
pulse height, into energy deposit PHA~i~ in MeV for detector i:

**TLM~i~**

**PHA~i~ = Factor~i~**

**1023**

where Factor~i~ can be either the low range factor or high range factor,
depending on the Low/High flag of the telemetered pulse height word.

  --------------------------- --------------------- ---------------------
  **Detector pulse height**   **Low range factor**  **High range factor**

  PHA_A                       3.00                  30.00

  PHA_B                       3.00                  45.00

  PHA_C                       16.07                 166.7

  PHA_D                       20.00                 225.00

  PHA_E                       20.00                 225.00
  --------------------------- --------------------- ---------------------