Chapter 5
International perspectives of neutron monitors
Sodankylä Geophysical Observatory, University of Oulu, Finland
The NM network is most useful as a joint network, which has much more abilities for science and applications than a sum of individual detectors. It is a balance between national and international efforts. It is crucially important that the NMs network is as homogeneous as possible without large gaps in coverage. For example, closure of NMs in the North America would result in a dramatic drop of quality of the NM network data in international perspective.
Data from individual NMs are gathered in several international databases:
World Data Center for Cosmic Rays (WDC CR) in Japan [http://center.stelab.nagoya-u.ac.jp/WDCCR], where all hourly-resolution data from NMs are collected in an ftp format;
Neutron Monitor Database (NMDB) in Germany [http://www.nmdb.eu] provides a user-friendly access to many long-operating NMs;
Ground Level Enhancement (GLE) data base [http://gle.oulu.fi] is an international database collecting all available data on GLE events recorded by the NM network.
The NM network is an international effort initiated at International Geophysical Year 1957. It provides a unique global network which is the primary instrument to study ”lower energy” (< 100 GeV/nuc) GCR, strong SEP events (GLE) and interplanetary transients (FD). The homogeneous NM data series exists for 60+ years forming a benchmark data set of cosmic rays and heliospheric/solar studies. The NM network has many advantages: it is a standard device, providing continuous monitoring of cosmic rays with stable operation, providing a homogenous data series; data are ready for real-time analysis; its response is known; important is low cost (distributed among different countries/institutions) and easy maintenance. The only disadvantage is that a NM is an energy integrating device, but this is overcome by the global networking, so that the NM network operates as a giant spectrometer using the Earth's atmosphere and magnetosphere.
The network cannot be replaced by space-borne instruments. The primary interest of many space-borne detectors (e.g., SOHO, ACE, GOES) is in solar transients, interplanetary medium and space weather, they have low energy range and cannot give an estimate for the atmospheric penetration of cosmic rays. Special CR-dedicated missions (PAMELA, AMS-02) are focused on high-energy exotic CR and HE astrophysics. The very complex DAQ system makes it difficult for real-time analysis. Because of the low inclined orbit only a fraction of time can be used to study SEP events. These detectors have limited life-time.
The NM network data is used for several fields:
Science
GCR variability (heliospheric modulation) – NMN is the primary instrument;
GLE analysis (source direction, anisotropy, spectra) – NMN is the primary instrument;
Solar neutron events – NMN is an important instrument ;
Interplanetary transients – NMN is a useful instrument.
Practical use
Aircraft crew dosimetry – NMN is the only instrument;
Space weather: storm fore/now-casts – NMN is an important instrument;
Chapter 6 Recommendations and priorities
Recommendations emerged from the workshop that if implemented would bring the network into a condition to conduct the best science and support operational needs. In order of priority, they are:
Fully restore the scientific functionality and update the existing US network. This will constitute a major step in restoring the global network by restoring coverage provided by the US stations and by making a statement to international funding agencies that the global network is important,
Establish a desired network concept that would fulfill the needs of the science and operational communities. This would involve identifying new key strategic sites to complete the global coverage,
Improve station and data uniformity and accessibility,
Train a new generation of scientists and expand educational outreach,
Given the unavailability of standard detectors, design and deploy a new generation of neutron monitors in the form of inexpensive kits to be widely deployed as part of global strategy for the network, and
Modernize or install new timing electronics to study rapid phenomena, not anticipated in 1957.
Student and Postdoc involvement in Neutron Monitors
The Newark and Durham Neutron Monitors are located on the campuses at the University of Delaware and University of New Hampshire respectively. These detectors have provided important teaching tools for undergraduates, graduate students and post docs over the years. These local stations gives students the opportunity to gain experience working on advanced instruments and high tech equipment. The operation of the system and detection strategy can be used to help engage students to explore physics and electronics from the basic level to the advance.
Need more
Neutron Monitors also provide a great opportunity to engage broader audiences. Novices are intrigued that the sun is not the steadily humming stellar engine typically portrayed, and among the science-interested public, there is an increasing awareness and interest in space weather.
Here we describe three ongoing efforts at the University of Wisconsin-River Falls (UWRF) that connects high school students, teachers, and undergraduate students to neutron monitor research. Besides exposing more people to astrophysics, these efforts provide access to new resources to support astrophysics research. These examples or similar programs are expandable to other institutions doing neutron monitor research.
UWRF, working with the Bartol Research Institute at the University of Delaware, has assumed responsibility for maintaining and operating the neutron monitor at the South Pole, and is playing a significant role in moving the neutron monitors on the coast of Antarctica at McMurdo Station to the Korean Jang Bogo base. We have leveraged the intrigue of the extreme Antarctic locale to garner broader interest in the research. To tap into new funding streams, the UWRF National Science Foundation proposal committed to utilize undergraduates, targeting students from two year colleges and underrepresented groups. Three students have deployed, one in the 2014-15 season and two in the 2015-16 season, and they kept blogs (https://i3uwrf.wordpress.com/) describing their experiences. Six students in total have done fully supported research at UWRF during the last three summers (2013-15).
We have also worked with the NSF PolarTrec (https://www.polartrec.com/) program that pairs teachers and researchers who have projects in the Arctic or Antarctic. This is a great way to leverage resources as PolarTrec handles logistical training, helps delineate and define the expectations for both the teacher and researcher, and monitors follow through, including resource development. This usually includes classroom or public outreach activities, areas where teachers excel. We continue to work with high school science teacher Mr. Juan Botella (https://www.polartrec.com/expeditions/cosray-neutron-monitors), though he unfortunately was not able to deploy at the last minute in the 2015-16 season. We have selected high school and two year college teacher Mr. Eric Thuma (https://www.polartrec.com/expeditions/antarctic-neutron-monitors-for-solar-study) to deploy with us in the 2016-17 season.
To reach high school students directly, we also work with the UWRF Upward Bound (https://www.uwrf.edu/AcademicSuccess/Upward-Bound.cfm) program, providing a summer eight-day math and science residential course for a highly diverse group of 9-12 students. Upward Bound (http://www2.ed.gov/programs/trioupbound/index.html) is a nation-wide federally funded program to help low-income high students prepare for success in college. Rather than focus exclusively on astrophysics, we pick a theme each year, and build from familiar accessible experiences to more complex, abstract concepts. We spend at least one day describing the research we do at UWRF that includes undergraduate students, and emphasize that the Upward Bound students could also be part of a research team in a few years.
Right to Left: Northern Illinois student Robert Zill with UW-River Falls professor Jim Madsen and student Laura Moon atop Observation Hill, near the site of the Cosray neutron monitor, McMurdo Station, Antarctica (Jan. 2016, Robert Zill Photo).
Chapter 7
Neutron Monitor Citations
Chapter 8
References
Table of Acronyms (incomplete)
NM Neutron Monitor
IGY International Geophysical Year 1957
IGY Simpson style Neutron Monitor 1949
NM64 Neutron Monitor designed by Carmichael and Hatton 1964
GLE Ground Level Event
SEP Solar Energetic Particles
IAGA International Association of Geomagnetism and Aeronomy
SWORM Space Weather Operations, Research, and Mitigation SWORM Task Force
SEU Single-Event Upsets
UNSCEAR United Nations Scientific Committee on the Effects of Atomic Radiation
DHS Department of Homeland Security
FAA Federal Aviation Administration
LANL Los Alamos National Laboratory
GCR Galactic Cosmic Rays
NMDB Neutron Monitor Database
START Strategic Arms Reduction Treaty
RDE Radiation Detection Equipment
NCRP National Council on Radiation Protection and Measurements
NUSTL National Urban Security Technology Laboratory
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