tbr cbt 2 ps question 25 regarding beta decay

[AntonFreeman]

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An impurity in an organic sample that would cause a scintillation counter to estimate the age of the sample as younger than it really is could include foreign material that can undergo: (Carbon decays to Nitrogen from passage)

A.Beta Decay
B.Beta Capture

I thought it was beta capture because more of Carbon you have, it will make the carbon seem younger than is right? Answer is Beta Decay.

 

[whiteshadodw]

An impurity in an organic sample that would cause a scintillation counter to estimate the age of the sample as younger than it really is could include foreign material that can undergo: (Carbon decays to Nitrogen from passage)

A.Beta Decay
B.Beta Capture

I thought it was beta capture because more of Carbon you have, it will make the carbon seem younger than is right? Answer is Beta Decay.

during beta decay a particle is emitted. this particle can be reacted with a 'scintillating agent/scintillant" or w/e. basically, the scintillating agent is something that changes colors, produces electricity, or something when it absorbs beta particles from the carbon. if the carbon was undergoing beta capture, how would you detect this?

 

[MD Odyssey]

An impurity in an organic sample that would cause a scintillation counter to estimate the age of the sample as younger than it really is could include foreign material that can undergo: (Carbon decays to Nitrogen from passage)

A.Beta Decay
B.Beta Capture

I thought it was beta capture because more of Carbon you have, it will make the carbon seem younger than is right? Answer is Beta Decay.

Well, electron capture occurs when a proton and an electron combine to form a neutron, which would lower the Z by 1, thus forming boron. β-decay can occur, where a neutron decays into a proton, an electron, and an anti-electron neutrino. This additional proton increases Z by 1, forming nitrogen. Clearly, β-decay is the only correct answer.

 

[Sbr2250]

An impurity in an organic sample that would cause a scintillation counter to estimate the age of the sample as younger than it really is could include foreign material that can undergo: (Carbon decays to Nitrogen from passage)

A.Beta Decay
B.Beta Capture

I thought it was beta capture because more of Carbon you have, it will make the carbon seem younger than is right? Answer is Beta Decay.

No, you guys have it wrong. The Scintillator is measuring the RATE of B-decay a substance is undergoing. So, if you add a foreign compound that is also undergoing B-decay at the same time, but is not carbon, it is effectively showing an increase in this rate. An increase in this rate indicates a younger sample, because increased rate would normally be due to a greater amount of C14 undergoing this decay. A greater amount of C14 = younger sample.

The key point is that scintillators are not simply measuring the total number of B-particles given off, but the current rate at which B-particles are being given off.

Hope this helps!