PDS_VERSION_ID = PDS3
RECORD_TYPE = STREAM
INTERCHANGE_FORMAT = ASCII
INSTRUMENT_HOST_NAME = "CASSINI ORBITER"
INSTRUMENT_HOST_ID = "CO"
INSTRUMENT_NAME = "MAGNETOSPHERIC IMAGING INSTRUMENT"
INSTRUMENT_ID = "MIMI"
OBJECT = ASCII_DOCUMENT
DOCUMENT_NAME = "
CHEMS PULSE HEIGHT ANALYSIS ALGORITHM DESCRIPTION"
DESCRIPTION = "(Title page information follows.)
----------------------------------------------------------------------
Cassini Mission
Magnetospheric Imaging Instrument
CHEMS Pulse Height Analysis Algorithm Description
Version 2.0
rev. February 28, 2005
J. W. Manweiler
Fundamental Technologies, LLC
Lawrence, KS 66046
---------------------------------------------------------------------- "
PUBLICATION_DATE = 2005-03-01
DOCUMENT_TOPIC_TYPE = "ALGORITHM SPECIFICATION"
INTERCHANGE_FORMAT = ASCII
DOCUMENT_FORMAT = TEXT
END_OBJECT = ASCII_DOCUMENT
END
FILE CONTENTS: Calibration algorithm for PDS data products containing
Cassini/MIMI/CHEMS PHA rates
AUTHOR: Jerry W. Manweiler, Ph.D., Fundamental Technologies, LLC
DATE: 03/01/2005
INTRODUCTION:
This file contains a text and pseudo code algorithm to provide a means to use
the PHA rates PDS data products for the determination of the health of the
CHEMS instrument and underlying science rates algorithm performance. In high
rate periods this data may be used to provide normalization of the science
rates.
ALGORITHM:
The following set of equations allows for the solution of the mass and/or
mass/charge of incident particles
RESULT VARIABLES:
M/Q = 2(tau/dist)^2*(E'/Q)
Q = (Energy/alpha)/(E'/Q)
M = 2(tau/dist)^2*(Energy/alpha)
E = Q(E/Q)
INPUT VARIABLES FROM A DATA PRODUCT:
tau: CPHA:dp:Time_of_Flight(Microsec)/1000000 (in seconds), the time of
light measured
Energy: CPHA:dp:Energy(keV), the measured energy deposited in the SSD
step: CPHA:dp:DPPS_Level, the deflection system potential step number
INPUT VARIABLES FROM A CALIBRATION FILE:
dist: CPHA:cdf:sep_distance(cm)/100 (in m), the separation distance
between the microplates
(E/Q): CPHA:cdf:step_(step)_E/Q(keV/e), E/Q for the given step number
VARIABLES TO BE PROVIDED BY DATA USERS:
alpha: the loss of the particle incident energy due to Pulse Height Defect
(nuclear defect) and not measured by the SSD - a number always less
than 1
GENERAL Cassini/MIMI CALIBRATION:
Each data product type in the PDS Cassini/MIMI Level 1A data set has two
associated calibration files: a calibration algorithm file that is specific to
each sensor and a calibration data file that is specific to the instrument.
Each calibration algorithm file (this file) contains a text and pseudo code
algorithm that describes how to calibrate the Level 1A data. The calibration
data file is a CSV file that contains data values used in the algorithm
described in the calibration algorithm file.
All records for a data product type in the PDS level 1A files and the
calibration data files have the same format. The first field in each record is
the purpose field. The purpose field indicates the intended use of the record.
For example records containing science data have a purpose field with the
value "sci" and a record containing the geometrical factors of the detectors
in a sensor would have "geom" in the purpose field.
All MIMI calibration algorithm files use a short hand notation to refer to
fields in the data products and calibration data files. This shorthand
notation consists of an instrument/data type, a file type, a purpose field
value, and a column description. This notation is used to specify types of
fields, in types of records, in types of files. This notation allows the
algorithm file to specify the relationship between types of fields in various
files. The syntax and examples of this notation are given below.
SHORTHAND NOTATION:
❮file type❯:❮sensor data type❯:❮row field value 1❯:❮row field value 2❯:...:
❮row field value n❯:[❮column id❯]
where:
❮file type❯ = dp or cdp where dp = data product and cdp = calibration data
product
❮sensor data type❯ = CACC, CPHA, CSCI, IACC, IIMG, IPHA, IACC, LFRT. The cdp
oes not include a ❮sensor data type❯ identifier.
❮row field value x❯ = a specification of a particular value of a row in order
of left to right for those rows that apply. It is notec that not all rows
apply for each value. Literal values of identifiers are placed in double
quotation marks. Variable values are in parenthesis "( )".
❮column id❯ = a column identifier (label) to be used to select the final
unique value based upon the combination of row identifiers and the specific
column that has the data value. Literal values are placed in double quotation
marks. Variable values are in parenthesis "( )".
examples:
dp:IACC:"sci":["Start_Ephemeris_s"] =
The starting time of the record with a single row identifier of
"sci"
dp:IACC:"sci":("Start_Ephemeris_s"):[(datacolumntype)] =
A field representing a specific column of counts for a record that
includes "sci" and a starting time in the column that uses the
literal for the start time in a column that identifies the source
of the counts.
geom_factor = cdf:"GEOM_FACTOR":"ACC":"INCA":"DETECTOR":("Particle"):
("Start_Year"):("Start_DDOY"):["midpoint_value"] =
Select the value of the geometrical factor using the literal
"GEOM_FACTOR", "ACC", "INCA", "DETECTOR" rows and the variable rows
for start year and DDOY (decimal day of year) in the column of
"midpoint_value".
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