Energy Spectrum of Neutrons from Spontaneous Fission of Californium-252

Hjalmar, Elis; Slätis, Hilding; Thompson, S.G.

doi:10.1103/physrev.100.1542

Cited by 7 publications

(3 citation statements)

References 5 publications

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“…6,8~10 In addition, the neutron spectrum resulting from the spontaneous fission of Cf 262 has been measured. 11,12 The experimental results are, generally, consistent with the statistical theory of prompt fission neutron emission. 13 In order to obtain information that will extend our knowledge of the fission process and to provide data useful in applied work this study of the prompt fission neutron spectrum of Pu 241 was undertaken.…”

supporting

confidence: 77%

Prompt Fission Neutron Spectrum ofPu241

1961

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The energy distribution of prompt neutrons resulting from the thermal-neutron-induced fission of Pu 241 is measured. Fast time-of-flight techniques are employed in the neutron energy range 0.3 to 6.0 Mev. Proton recoils in emulsions are utilized for the measurement of neutron energies from 1.6 to 7.0 Mev. The experimentally determined Pu 241 fission neutron spectrum is well represented by the Maxwellian distribution, N(E) ccEh~E /T , where E is the neutron energy in Mev, N(E) the number of neutrons per unit energy interval, and T= 1.335±0.034 Mev. The measured average Pu 241 fission neutron energy is 2.002±0.051 Mev.

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confidence: 77%

Prompt Fission Neutron Spectrum ofPu241

1961

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“…In practice, the ends of the tubes ranged from around 6.5 to 10 cm away from the source, so we can expect a 2.4 • higher fluence at the base of a long tube relative to the estimate. The mean free path of a neutron also contributed to total variation in fluence: 252 Cf has a most probable neutron energy of 0.7 MeV and average neutron energy of 2.1 MeV (Hjalmar, 1955;Singleterry and Thibeault, 2000). In water, the neutron mean free paths at these energies are 2.3 and…”

Section: Neutron Exposurementioning

confidence: 99%

Radiation Resistance of Biological Reagents for In Situ Life Detection

et al. 2013

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Life on Mars, if it exists, may share a common ancestry with life on Earth derived from meteoritic transfer of microbes between the planets. One means to test this hypothesis is to isolate, detect, and sequence nucleic acids in situ on Mars, then search for similarities to known common features of life on Earth. Such an instrument would require biological and chemical components, such as polymerase and fluorescent dye molecules. We show that reagents necessary for detection and sequencing of DNA survive several analogues of the radiation expected during a 2-year mission to Mars, including proton (H-1), heavy ion (Fe-56, O-18), and neutron bombardment. Some reagents have reduced performance or fail at higher doses. Overall, our findings suggest it is feasible to utilize space instruments with biological components, particularly for mission durations of up to several years in environments without large accumulations of charged particles, such as the surface of Mars, and have implications for the meteoritic transfer of microbes between planets.

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“…Previously, californium-252 ( 252 Cf) was used for desorption mass spectrometry. − However, the source design operates under reduced-pressure conditions, and the samples need to be deposited on a substrate using an ESI method before sampling, making it not ambient. In addition, 252 Cf is a very strong neutron emitter (1 μg of 252 Cf emits 2.3 million neutrons per second), so it is extremely harmful, − limiting its wide applications. In addition, nickel-63 was employed as an atmospheric pressure electron source through β decay for mass spectrometric analysis. − However, this method was only applied for gaseous molecules carried by N 2 .…”

mentioning

confidence: 99%

An ²⁴¹Am Plasma Desorption Ionization (AmDI) Source Scavenged from Smoke Detectors for Ambient Mass Spectrometry Sampling

Dong

Liang

et al. 2022

Anal. Chem.

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The development of efficient, low-cost, easy-to-use ambient ionization methods has been a major goal of modern mass spectrometry. In this Letter, we present a gas-free, voltage-free, economic, and safe desorption ionization method using the plasma generated by a radioactive element, americium-241, scavenged from smoke detectors that equip almost every household. No other energy sources, such as laser, discharge, fast-moving carrier gas, solvent droplet, ultrasound, or heat are needed. We name this new method as americium-241 desorption ionization (AmDI). AmDI is tested for the detection of more than 20 volatile and nonvolatile chemicals under different sampling conditions, and the detection limit can be in the range of tens of picograms for some analytes. Mechanistically, we provide evidence that the α particles emitted from radioactive decay ionize ambient air, and the resulting plasma further energizes and ionizes the surface analytes for mass spectrometry detection. We anticipate wide applications of AmDI in mass spectrometric sampling in the near future because of the plethora of merits.

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Energy Spectrum of Neutrons from Spontaneous Fission of Californium-252

Cited by 7 publications

References 5 publications

Prompt Fission Neutron Spectrum ofPu241

Prompt Fission Neutron Spectrum ofPu241

Radiation Resistance of Biological Reagents for In Situ Life Detection

An ²⁴¹Am Plasma Desorption Ionization (AmDI) Source Scavenged from Smoke Detectors for Ambient Mass Spectrometry Sampling

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Energy Spectrum of Neutrons from Spontaneous Fission of Californium-252

Cited by 7 publications

References 5 publications

Prompt Fission Neutron Spectrum ofPu241

Prompt Fission Neutron Spectrum ofPu241

Radiation Resistance of Biological Reagents for In Situ Life Detection

An 241Am Plasma Desorption Ionization (AmDI) Source Scavenged from Smoke Detectors for Ambient Mass Spectrometry Sampling

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Product

Resources

About

An ²⁴¹Am Plasma Desorption Ionization (AmDI) Source Scavenged from Smoke Detectors for Ambient Mass Spectrometry Sampling