The time taken for the radioactivity of an isotope to fall to half of its original value.
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What is a positron?
a positive beta particle emitted from a nucleus deficient in neutrons
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What is a beta particle?
a negative electron emitted from a nucleus with excess neutrons
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What is the use of iodine-125?
labelling peptides
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What is the use of hydrogen-3 (tritium)?
labelling sugars
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What is the use of sulphur-35?
labelling proteins and DNA sequencing (S replaces O in phosphate)
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What is the use of phosphorous-32?
labelling nucleic acids
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How many neutrons does tritium have?
2
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What is the range of P32 in air?
790cm
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What is the range of S35 in air?
26cm
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What is the range of tritium in air?
6mm
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When was the Radioactive Substances Act formed and what does it involve?
1993; concerned with keeping records of use, accumulation and disposal. Registration of users; establishments and people
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When was the Ionising Radiation Regulations formed and what does it involve?
1999; Safety at work of users and others, requires users to be competent, implies there is adequate training in place, transgressions are deemed to be criminal offences
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What is the inverse square law?
Energy of radiation decreases in proportion to the square of the distance from its source, also affected by air and other substances
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What type of radiation has the longest range?
Gamma and X-ray
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What type of radiation has the highest contamination risk
alpha
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What type of radiation is phosphorous-32?
beta - high energy electrons
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What type of radiation is sulphur-35?
beta - low energy electrons
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What type of radiation is tritium?
beta - very low energy electrons
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What type of radiaiton is iodine-125?
Gamma and X-ray
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How are the different isotopes in life sciences detected?
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