Cosmic Ray Instruments Research Articles

China's Ground‐Based Space Environment Monitoring Network—Chinese Meridian Project (CMP)

AbstractMonitoring and investigation of the solar‐terrestrial space environment is a huge challenge for humans in space age. To this end, China has established the Ground‐based Space Environment Monitoring Network, namely Chinese Meridian Project (CMP). The project comprises three major systems: the Space Environment Monitoring System, Data and Communication System, and Scientific Application System. The Space Environment Monitoring System adopts a well‐designed monitoring architecture, known as “One Chain, Three Networks, and Four Focuses,” to achieve stereoscopic and comprehensive monitoring of the entire solar‐terrestrial space. The “One‐Chain” component utilizes optical, radio, interplanetary scintillation, cosmic ray instruments to cover the causal chain of space weather disturbances from the solar surface to near‐Earth space. For the ionosphere, middle and upper atmosphere, and magnetic field, instruments are deployed along longitudes of 120° and 100°E, and latitudes of 30° and 40°N, forming the “Three Networks.” Furthermore, more powerful monitoring facilities or large‐scale instruments have been deployed in four key regions: the high‐latitude polar region, mid‐latitude region in northern China, low‐latitude region at Hainan Island, and the Tibet region. These four regions are crucial for disturbances propagation and evolution, or possess unique geographical and topographical characteristics. The Data and Communication System and Scientific Application System are designed for data collecting, processing, storage, mining, and providing user service based on data acquired by the Space Environment Monitoring System. The data obtained by CMP will be shared with the global scientific community, facilitating enhanced collaboration on space weather and space physics research.

A novel synthetic diamond Cherenkov radiator for measuring space radiation

The measurement of cosmic rays and Solar energetic particles in space is basic to our understanding of the Galaxy, the Sun, phenomena in the Heliosphere and the emerging field of space weather . For these reasons, cosmic ray instruments are common on both scientific spacecraft and operational spacecraft such as weather satellites. Cosmic rays (CRs) and Solar energetic particles (SEPs) include ions over the full range of elements found in the Solar System. High-resolution measurements of the energy spectra of space radiation are key to understanding both acceleration and propagation processes. An inherent challenge is the large range of energies of such spectra. Cosmic ray energies range up to over 1 0 21 eV , while SEPs can reach a few GeV. Multi-instrument measurements are currently required to cover the full range of particle energies. Indeed, the highest energy particles, due to the rarity, can only be measured with ground-based instruments using the atmosphere as a calorimeter . Over limited energy ranges, SEP spectra are often approximated by a power law; however, over the full energy range, SEP events exhibit changing spectral shapes (e.g. “knees”, “roll-overs” and “cut-offs”). These features give information about the acceleration processes, such as size of the acceleration region, time of acceleration, morphology of the magnetic field during acceleration, and others, all of which can vary from event to event. Measurements of such features are often compromised by the need to combine measurements from more than one instrument, each with its own limited energy range. Even if there are no gaps between the energy intervals of the instruments, differing systematics can severely impact data analysis. A single instrument capable of measurements over a continuous and extended energy range would offer vastly more reliable measurement of the energy spectra of SEP events as well as replacing multiple instruments on resource-limited spacecraft. The most common method to measure GCRs and SEPs from a few to ∼ 100 MeV for protons, is Si Solid-State Detector (SSD) stacks. Above these energies, Cherenkov detectors are typically used together with SSDs. Ideally, to provide full energy coverage with no gaps, this requires a Cherenkov radiator with a threshold of ∼ 100 MeV. No suitable Cherenkov detector with such a low threshold has been developed. We are in the process of developing a synthetic diamond Cherenkov detector for this purpose. Diamond’s high index of refraction (2.42) results in a theoretical threshold of 92 MeV for protons. Even with a practical threshold of ∼ 110 MeV, this is ideal for extending the energy range from that of SSDs alone to that of sapphire Cherenkov detectors (202 MeV threshold) with higher energies attainable using plastic Cherenkov detectors. Both Sapphire and plastic Cherenkov radiators have spaceflight heritage.

Questions surround NASA’s shutdown of an international cosmic-ray instrument

The detector aboard the International Space Station could be turned back on if a new proposal passes peer review. But it’s unclear who might operate it.

Accelerator test of an improved Angle Detecting Inclined Sensor (ADIS) prototype with beams of 78Kr and fragments

The measurement of cosmic rays and Solar energetic particles in space is basic to our understanding of the Galaxy, the Sun, phenomena in the heliosphere and the emerging field of space weather. For these reasons, cosmic ray instruments are common on both scientific spacecraft and operational spacecraft such as weather satellites.Cosmic rays and Solar energetic particles include ions over the full range of elements found in the Solar System. High-resolution measurements of the elemental and isotopic composition require the angle of incidence of these energetic ions be determined to correct for pathlength variation in detectors within an instrument. The Angle Detecting Inclined Sensor (ADIS) system is a simple detector configuration used to determine the angle of incidence of heavy ions in space instruments. ADIS replaces complex position sensing detectors (PSDs) with a system of simple, reliable and robust detectors inclined at an angle to the instrument axis. An ADIS instrument thus offers significant advantages in mass, power, telemetry and cost.In February 2008 an improved ADIS prototype was tested with a 150MeV/u 78Kr beam at the National Superconducting Cyclotron Laboratory's (NSCL) Coupled Cyclotron Facility (CCF). This demonstrated a charge resolution of σ~0.3 e at Kr (Z=36), an exceptional charge resolution for such a simple instrument system.

Suprathermal ions in the solar wind from the Voyager spacecraft: Instrument modeling and background analysis

Using publicly available data from the Voyager Low Energy Charged Particle (LECP) instruments, we investigate the form of the solar wind ion suprathermal tail in the outer heliosphere inside the termination shock. This tail has a commonly observed form in the inner heliosphere, that is, a power law with a particular spectral index. The Voyager spacecraft have taken data beyond 100 AU, farther than any other spacecraft. However, during extended periods of time, the data appears to be mostly background. We have developed a technique to self-consistently estimate the background seen by LECP due to cosmic rays using data from the Voyager cosmic ray instruments and a simple, semi-analytical model of the LECP instruments.

Theory and application of measuring mesoscale soil moisture by cosmic-ray fast neutron probe

In recent years, measurement of surface soil moisture by the cosmic-ray fast neutron probe has gradually attracted more attention The intensity of the fast neutrons above the ground is sensitive to water content changes, largely insensitive to soil chemistry and inversely correlated with hydrogen content of the soil. Measurement of this intensity with a portable neutron detector placed above the ground permits the possibility of monitoring soil moisture. By this passive, non-invasive and intermediate scale measurement, soil moisture at a horizontal scale of around 660 m and depths of 12 to 76 cm can be inferred. And the large footprint makes this method suitable for weather and short-term climate forecast initialization and for validation of soil moisture inversed from satellite sensors. In this paper, the results of the cosmic-ray instruments well reflected the variation trend of soil moisture at the field scale. We found that irrigation and infiltration were two most important factors that affected the variation of soil moisture during a growing season of maize in Zhangye and the soil moisture of different period in the growing season of maize was very different. At last, Wireless Sensor Network data were used to validate this result and we found their correlation was very well with a RMSE of 0.0275 m3m−3 in the non-irrigation time.

Accelerator test of an angle detecting inclined sensor (ADIS) prototype with beams of 48Ca and fragments

The measurement of cosmic rays and Solar energetic particles in space is basic to our understanding of the Galaxy, the Sun, phenomena in the Heliosphere and what has come to be known broadly as “space weather”. For these reasons, cosmic ray instruments are common on both scientific spacecraft and operational spacecraft such as weather satellites. The resource constraints on spacecraft generally mean that instruments that measure cosmic rays and Solar energetic particles must have low mass (a few kg) and low power (a few W), be robust and reliable yet still highly capable. Such instruments must identify ionic species (at least by element, preferably by isotope) from protons through the iron group. The charge and mass resolution of heavy ion instruments in space depends upon determining ions’ angles of incidence. The Angle Detecting Inclined Sensor (ADIS) system is a highly innovative and uniquely simple detector configuration used to determine the angle of incidence of heavy ions in space instruments. ADIS replaces complex position sensing detectors (PSDs) with a system of simple, reliable and robust Si detectors inclined at an angle to the instrument axis. In August 2004, we tested ADIS prototypes with a 48Ca beam at the National Superconducting Cyclotron Laboratory's (NSCL) Coupled Cyclotron Facility (CCF). Among the analyses performed on the data taken at the NSCL, we demonstrate that our prototype design with an ADIS system has a charge resolution of less than 0.25 e. We also present a more generalized analytic derivation of instrument response and report on the corresponding analysis of Monte-Carlo modeling data.

Waveshifting fiber readout of lanthanum halide scintillators

Newly developed high-light-yield inorganic scintillators coupled to waveshifting optical fibers provide the capability of efficient X-ray detection and millimeter scale position resolution suitable for high-energy cosmic ray instruments, hard X-ray/gamma ray astronomy telescopes and applications to national security. The CASTER design for NASA's proposed Black Hole Finder Probe mission, in particular, calls for a 6–8 m 2 hard X-ray coded aperture imaging telescope operating in the 20–600 keV energy band, putting significant constraints on cost and readout complexity. The development of new inorganic scintillator materials (e.g., cerium-doped LaBr 3 and LaCl 3) provides improved energy resolution and timing performance that is well suited to the requirements for national security and astrophysics applications. LaBr 3 or LaCl 3 detector arrays coupled with waveshifting fiber optic readout represent a significant advance in the performance capabilities of scintillator-based gamma cameras and provide the potential for a feasible approach to affordable, large area, extremely sensitive detectors. We describe some of the applications and present laboratory test results demonstrating the expected scintillator performance.

Variations in the cosmic radiation, 1890–1986, and the solar and terrestrial implications

Comparison of cosmogenic 10Be data and the records from several independent cosmic ray instruments for the period 1933–1977 demonstrates that the 10Be data provide a reliable measure of the ∼2 GeV/nucleon cosmic ray intensity at Earth, over short (∼5 years) and long (>20 years) time scales. The 10Be data show that the cosmic ray flux at sunspot minimum was anticorrelated with Z min, the sunspot number at solar minimum over the interval 1901–1986. There was a 26% enhancement in the 10Be data in the interval 1951–1954, and the data from two independent cosmic ray instruments verify that this was due an influx of low energy (<3 GeV/nucleon) cosmic radiation. It is suggested that this enhancement was associated with the very low sunspot number in 1954 (one of the lowest outside the Maunder and Dalton Minima), and with an anomalous cosmic ray diurnal variation in 1954. It is proposed that these several observations are the consequence of cosmic ray drift effects, and that the heliomagnetic field was relatively ordered in 1954. It is shown that the enhancement of 1954 is not consistent with the several models of the open solar magnetic field, unless factors other than the magnetic field strength are taken into account. Using the instrumental and 10Be data, the cosmic ray spectra are estimated for 1965, 1954, 1890–1895, 1810–1820, and 1680–1720. From these, the ionization in the Earth's polar atmosphere is estimated for each of these periods.

Th/U/Pu/Cm dating of galactic cosmic rays with the extremely heavy cosmic ray composition observer

The principal goal of ECCO, the Extremely-heavy Cosmic-ray Composition Observer, is the measurement of the age of heavy galactic cosmic-ray nuclei using the extremely rare actinides (Th, U, Pu, Cm) as clocks. ECCO is one of two cosmic-ray instruments comprising the Heavy Nuclei Explorer (HNX), which was recently selected as one of several missions for Phase A study under NASA's Small class Explorer (SMEX) program. ECCO is based on the flight heritage of Trek, an array of barium-phosphate glass tracketch detectors deployed on the Russian space station Mir from 1991–1995. Using Trek, we measured the abundances of elements with Z > 70 in the galactic cosmic rays (GCRs). Trek consisted of a 1 m2 array of stacks of individually polished thin BP-1 glass detectors. ECCO will be a much larger instrument, but will achieve both excellent resolution and low cost through use of a novel detector configuration. Here we report the results of recent accelerator tests of the ECCO detectors that verify detector performance. We also show the expected charge and energy resolution of ECCO as a function of energy.

Composition of anomalous cosmic rays and implications for the heliosphere

We use energy spectra of anomalous cosmic rays (ACRs) measured with the Cosmic Ray instrument on the Voyager 1 and 2 spacecraft during the period 1994/157–313 to determine several parameters of interest to heliospheric studies. We estimate that the strength of the solar wind termination shock is 2.42 (-0.08, +0.04). We determine the composition of ACRs by estimating their differential energy spectra at the shock and find the following abundance ratios: H/He = 5.6 (-0.5, +0.6), C/He = 0.00048 ± 0.00011, N/He = 0.011 ± 0.001, O/He = 0.075 ± 0.006, and Ne/He = 0.0050 ± 0.0004. We correlate our observations with those of pickup ions to deduce that the long-term ionization rate of neutral nitrogen at 1 AU is ~ 8.3 x 10-7 s-1 and that the charge-exchange cross section for neutral N and solar wind protons is ~ 1.0 x 10-15 cm2 at 1.1 keV. We estimate that the neutral C/He ratio in the outer heliosphere is 1.8(-0.7, +0.9) x 10-5. We also find that heavy ions are preferentially injected into the acceleration process at the termination shock.

Angular distributions of energetic charged particles observed with HELIOS-1 and -2 between 0.3 and 1 AU and their relevance to manned interplanetary space missions

The University of Kiel Cosmic Ray Instrument on board the solar probes HELIOS-1 and -2 measured angular distributions of electrons, protons, and heavier nuclei between 0.3 and 1 AU over one complete solar cycle between 1974 and 1986. Anisotropies are observed mainly during the rising phase of solar particle events or close to the passage of certain interplanetary shocks. The anisotropies are presented as proton data of energies between 27 and 37 MeV. The dependence of the anisotropies on particle energy and distance from the sun is provided based on diffusive propagation in interplanetary space. Strong anisotropies could provide a chance of efficient shielding of the passenger compartment by moving heavier parts of the spacecraft structure into the direction of the highest flux. A reduction of the total radiation dose by less than a factor of 2 might be achievable, however, selection of quiet times for the mission reduces the radiation hazard much more.

Interplanetary radial gradients of galactic cosmic ray protons and helium nuclei: Pioneer 8 and 9 measurements from 0.75 to 1.10 AU

We report measurements of the radial interplanetary cosmic ray gradient made with cosmic ray instruments aboard the Pioneer 8 and 9 spacecraft. The time period covered in these studies is from January 1968 to June 1969. During this time, the radial separation of these two spacecraft varied from 0.75 to 1.10 AU from the sun. This study includes detailed measurements of the differential spectra and gradients of protons and helium nuclei from 2 to 1200 Mev/nucleon. The differential gradient for each species is observed to go through a broad maximum of about 50%/AU at energies corresponding to about 1 BV rigidity, decreasing at both lower and higher rigidities. The proton and helium nuclei gradients are small down to the lowest energies we measure.-

A Solar and Galactic Cosmic Ray Satellite Experiment

A cosmic ray instrument for NASA's OGO-F spacecraft is described. The experiment consists of three charged particle detector systems which are designed to measure the spectra and chemical composition of galactic and solar cosmic rays over selected energy intervals. Two of the detector systems, the ?E-Range and ?E-?erenkov telescopes, will measure the galactic flux and smaller solar flare fluxes, while a third detector system, the Flare telescope, will measure larger fluxes The three telescopes identify particle energy and type by various techniques. Energy loss and range, which provide the identification of protons (1 to 300 MeV), alpha particles (4 to 1200 MeV) and electrons (1 to 500 MeV), are measured in a stack of silicon solid state detectors and tungsten absorbers in the ?E-Range telescope, while the identification of protons (350 to 1000 MeV), alpha particles (1400 to 4000 MeV) an, nuclei through oxygen is provided in the ?E-?erenkov telescope by energy loss measurements in silicon solid state detectors and a velocity measurement in a quartz & ?erenkov radiator. The Flare telescope employs a double energy loss measurement in silicon detectors for the identification of protons (17 to 100 MeV) and alpha particles (70 to 400 MeV). The design of the instrument is optimized for maximum use of the available data rate with minimum weight, volume and power requirements.