Cosmic Ray Latitude Survey: 1996-1997Entry ID: CosmicRayLatitudeSurv1996-1997
Abstract: During the 1996-97 austral summer, a period of solar minimum, we operated a
neutron monitor on board the ship Italica of the Italian Antarctic Programme to
record cosmic ray neutron intensities in seas from Italy to Antarctica and
back. This survey provided a full coverage of cut-off rigidities and the
possibility of repeating the measurements at least twice at the same cut-offs.
The main purpose ... of this research was the determination of an accurate latitude
curve of cosmic ray nucleonic intensity during solar minimum to be used for
obtaining the coupling function appropriate for this phase of solar cycle.
Accuracy was achieved through reliable instrumentation and proper control of
the experiment and by determining and applying for the first time all
corrections, for (1) changes in vertical atmospheric mass column, by taking
into account wind effect; (2) oscillations of the ship produced by sea
roughness; (3) atmospheric temperature changes; (4) primary cosmic ray temporal
variations including north-south asymmetry; and (5) temporal variations in the
cosmic ray east-west effect, caused by asymmetric shielding on the ship.
Start Date: 1996-12-20Stop Date: 1997-03-26
Quality The high-energy cosmic ray (CR) nucleonic component intensity was measured with
a standard neutron detector (of NM-64 type, extensively used all over the world
in several CR stations) made by three large BF3 proportional counters placed,
each of them, inside a lead structure, surrounded by a proper layer of
... Lead works as a neutron multiplier, due to the interactions (single or
multiple) between the energetic incoming particles (with energy E>50 MeV) of
the secondary nucleonic component and the lead nuclei. The surrounding
polyethylene acts as an inner-reflector for particles generated inside the
detector and, at the same time, as an outer-reflector for particles generated
out of the detector (for instance in high atomic number external structures).
Just around each counter a polyethylene tube (2 cm thick) acts as a neutron
thermalizer. The thermal neutrons are detected by the proportional counters.
Over the high-energy neutron detector, on the extreme left and right sides, two
additional BF3 counters without lead and polyethylene (bare counters B1, B2)
are utilized for recording the low energy neutrons (thermal background). The
instrumentation was installed inside a air-conditioned container capable of
maintaining the relative humidity below 55% and temperature between 18� and
25�C along the survey.
The data were recorded at 5-min intervals using a standard VXIbus data
acquisition system (the clock was inside the VXI). The following information
are obtained: (1) geographic position and universal time provided by a Global
Position System (GPS); (2) atmospheric pressure by a high precision device
utilizing a vibrating cylinder transducer (resolution 0.01 mbar, precision 0.1
mbar, stability 0.1 mbar per year); an additional pressure sensor (0.2 mbar
resolution) was also operating; (3) internal temperature and relative humidity
and external temperature; (4) the values of high and low voltages; (5) the
integral 5-min value of CR intensities measured by each counter of 3NM and of
bare counters); and (6) speed and direction of winds (provided by a companion
experiment). A spare acquisition system was foreseen and used with an external
computer supplied with a HP-basic co-processor.
Use Constraints To acknowledge the IFSI-CNR/UNIROMATRE collaboration and PNRA
Data Set Progress
Distribution Media: Floppy disk, CDROM
Distribution Format: ASCII
Fees: No cost but data acknowledgement is required.
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Creation and Review Dates
DIF Creation Date: 2005-01-01
Last DIF Revision Date: 2017-08-23