James Smallcombe: So, sorry about that. So sorry to everyone's joining the recording. I've got started.
James Smallcombe: And enjoy the rest of the talk.
Sean: So I'm having technical issues with my PowerPoint.
Sean: For us to move on. And so in the real world is
Sean: It's not quite as simple as just having that simple idealize in case game so you can hear you end up with multiple broad decay branches and multiple cameras and you can end up with conversion electrons.
Sean: And your beta detector can also be sensitive, a little bit to your gamma's so you need to those will have to be taken into account within your primary standard my daily what we're looking to do is find out what the the activity of the whole decay schemas and what
Sean: And through and find out what the activity if we went to 100% efficiency or the tree count like 100% efficiency will be
Sean: So we can do that by modifying the detection efficiency of one channel which is typically going to be the big channel because it's the easiest one to do
Sean: And there's multiple methods for doing this. You can foil the source, you can change the thresholds so
Sean: There's multiple ways of doing it, but through if by that you get lucky we measure the source and you get lots of activity measurements are different.
Sean: Or true or count rates or rates at different efficiencies and therefore we can extrapolate back to where the efficiency equals one. So it's an example. It's very simple one. So, so you may not always be linear, or may not always be this flat.
Sean: So within this work we've used. There's a lot of gamma ray spectrometry. And this is one of our typical setups with a lead coffin with multiple positions along that along an access. So, so we can make the source away.
Sean: And we can iterate these typically a long distance. So typically about 30 centimeters, because that gives us a very low solid angle which we can then
Sean: Reduces the problems of true quinson something. And these are and all of our and we calibrate these detectors using a suite of primary and secondary standards.
Sean: And giving the sort of efficiency calibrations. So these are all being fit with a be spline a cubit baseline. And because there's correlations between the different
Sean: Between the same gamma emissions being used for calibrating detected, we have to take into account the covariance is in the uncertainty of the efficiency curve.
Sean: You can get more information. If you want it from this paper about how we've fitted the calibration curve so thorough into seven
Sean: So it's 100% alpha decay has a half life of approximately 18.7 days and as quite complex to case game with 46 hour for transitions and so far. They're saying about 240 gamma transitions observed
Sean: One of the only issues is that has low gamma ray emission intensities, which makes it quite hard to detect and to form the coincidences.
Sean: And obviously one of the biggest issues is it never turns up on its own. If you have 37 you will have all the decay progeny along with it.
Sean: And in this spectrum here. This was taken about eight hours after the chemical separation. You can already see that there's quite a number of rating 23
Sean: And decay progeny coming through and they were marked off with an actress. So it grows in quite quickly. Initially, and can cause quite a lot of difficulties.
Sean: So here's the case game, and this is only partial because it's quite complex, as an adult, I think there's another four pages of these in the NSF data set.
Sean: But one of the key takeaways for this is that you're you've got about 24% to came straight to the ground state. And I should mention that these are all the, I guess intensities. The gamma is plus the conversion electrons.
Sean: So, and you can see there's not many. So these red ones are just over 10% so there's not many very significant gamma missions.
Sean: So going back to the temporal relationship. So that gets it gives us a chance to crack the payment equations which everybody enjoy so much
Sean: So we can see that the relationship of if we have to take away all of the radium and K progeny right the beginning, you'd see this
Sean: Quick this increase over time into a credit into transit and Calabrian and that when they there are all in equilibrium, your app. Your ratio for the activities about 16.46
Sean: Your, your observed in equilibrium. Your observed can rate would be 16 times more
Sean: But unfortunately, that doesn't happen for over 200 days. So that's more than 10 half lives authority seven. And so by the time you're trying to measure Thor entity seven in equilibrium that would be barely any bit left which poses significant difficulties for determining the activity.
Sean: So this is the physical characteristics of 37 quite useful for using photography of alpha Radio Alpha radiotherapy, so you can
Sean: Former antibody collector conjugate, which comes with 47 which can then be injected into a patient and because of the 18.7 day half life. It gives it enough time to move around the body and find the tumor and it's very targeted because of the antibody.
Sean: attached the tumor before it decays and therefore we can get once it attaches it once. If it reaches the tumor can decay and release an hour for a mission that
Sean: Has a high energy and short a short path length. So, which can hasn't high probability of damaging the DNA and causing double breaks, which if you get enough of them can kill the tumor cell very useful for trying to treat cancer.
Sean: So where we need the primary standard is for determining factors or calibration faxes radionuclides collaborators in medical clinics. When you clean medicine departments.
Sean: And we can see here the. So this is some real data. So on the captain tech. So you can see over time as the radium grows in, you get this increase in the response before it starts to come back down again.
Sean: But when you're considering the response of your collaborator, you need to consider that it's not be just the activities, but it's their relative responses, based on the gamma mentions they have
Sean: And their their their intensities and circles and you need these for modeling the response for the chamber and you can see that this cabin tech changes quite significantly around this region, and then going up.
Sean: So one of the challenges for performing a primary standardization authority, the seven wonders of revolt. I've already mentioned the engravers possibly the key factor here.
Sean: We have to remove the right into three because we need to measure the same standard on a calibrated to to radionuclides calibrated get that response curve.
Sean: And it means a total count rate is constantly changing the time and including during the measurement. So essentially just hitting a MOOC trying to hit a moving target. That's not following a not a normal exponential decay.
Sean: And then we need to know the some of the progeny of the time management because we need to divide the observed total count rate by the ratio of all the progeny to the
Sean: To the authority seven. So for that, we also need to know the last time since the separation. So I mean internet via to measure the time zero accurately where the activity is all all for him 27
Sean: servings. We need radio chemistry and it needs to be an effective or efficient and effective method for removing all that progeny.
Sean: We need good nuclear data because of the temporal dependence makes half lives critical for the accuracy and precision of the standardization.
Sean: And we need more accurate gamma ray emission intensities. Because currently, they quite precise.
Sean: And also we have the problems of the K project themselves. They have raid on to our nine which
Sean: Because of it is a gas will come off the source, so it can't be. You can't have a point source. So it has to be done by liquid sensitization technique.
Sean: And we also have planning to run five, which has a half life for 1.7 milliseconds. So because of the dead time, which can be around between 10 and 20 milliseconds. You can have it has a relationship with the raid on to our nine follows that can lead to a small loss of counts.
Sean: So where to start. So in this case, we started with the radium 33 because that is also a radio pharmaceutical and actually as the first one released
Sean: by a company called gator who were then bought by Bayer for $2 billion. If you have a good idea. It could make you some money.
Sean: So this is a drug was developed for treating men with advanced prostate cancer. So this is where the cancer metastasized and travel around to the bones around the body.
Sean: So this is only for palliative care. This is not a cancer treatment itself that's going to kill you, but it will give you a better quality of life.
Sean: And I think the research showed all the clinical trials showed that it can give you three to six months. Extra Life expectancy in a much higher quality of life. So since radium is a
Sean: Quick. What is the same as calcium chemically what chemistry wise because there and make sure they're in the same group.
Sean: It gets included into the bone structure when it in the world where the bonus reconstitution itself nearby the to the tumor, so therefore it can deliver its affirmations directly, it can to the tumors.
Sean: But because you also have a number of other offers. It's not just the alpha radium two to three. Sorry. It's the have alphas from a number of the other progeny as well decaying in the same space.
Sean: So why is it useful for something here. So we need new absolute gamma ray emission intensities because we're going to need them for determining the time zero, because we're looking for an activity ratio and we need this precisely
Sean: And we also need to make corrections and authority MTD seven for the gamma ray emission intensities. And we also need to write into three calibration factor for an ionization chamber measurements.
Sean: So again, this has a has a again has a relationship with his progeny, a bit like has all the same question is 27 but because of the difference in the half life of the project for right into three a much shorter
Sean: These can reach the equilibrium. Within about 10 hours of being separated. So it's a much simpler process. I just wait 10 hours you measure it and then you just need to divide by six and a bit as we're showing up here.
Sean: So the first time diarization of raiding two three was performed a nest, and this was used for defining the traceability and that's been using nuclear medicine department of the time.
Sean: And they did it by liquid sent techniques and by to pipe or portion accounting and you can see here that there's a slight difference and all these uncertainty bars are cables to there's a difference between the germanium results and the other primary standardization techniques.
Sean: So one thing to realize is that there was a dilution between the Germania measurements, the measurements of the solution was measured by the germanium sector and the measurements are done by the primary techniques.
Sean: So when we did it.
Sean: We did the standardization MPL we did it by a number of primary standard techniques. But we also thereby be also did gamma ray spectrometry. And you can see here that we don't seem to see the same differences that Ness or
Sean: So they ignored. So the differences in there between the domain of results.
Sean: But when we come back and we compared the MPL and the next ionization chamber calibration factors because we share our noses Asian chamber that's quite similar.
Sean: We noticed that as a 10% difference which was a bit concerning we thought we'd had a bit of a problem. But actually, when it comes down to it.
Sean: When nested their standardization and they kind of ignored the germanium results. It's for good reason. The as an 18% spread
Sean: In the results of the germanium using the main gamma lines of the rating two three indicate Virginie so you can understand why they probably just said the nuclear data is a bit rubbish, we won't worry about it too much.
Sean: But actually if you look at business to up to 11 it's very good marker, because it's a very simple decay scheme and it's very easy to determine the absolute mission intensity theoretically
Sean: So you can use that to go, well, it's quite a good result. And I think the activities around about there.
Sean: So what it actually turns out to be is the radium chloride was unstable in their nest in their solution. So, where they did a dilution between
Sean: This the measurement, the solution they use for this and solution they use for this for the primary standard they'd lost the amount of activity.
Sean: So they since then they've had to revise their standard, but obviously there have also had to go and revise all of the calibration factors for the rating nucleic collaborators, which has caused a bit of money.
Sean: So using these problem you can you use these primary standards we can derive the absolute values because we don't need to know
Sean: Or we can bypass and need to know the internal conversion coefficients, because we have different determine the activity and an absolute manner, without any relation to weekly data or efficiency curves or anything else. So
Sean: As expected, is from. You can see from that plot we get a mind that we get these big differences between the major families, we've measured and the previous recommended values.
Sean: But soon as we've done this measurement, these, these numbers are nest and painting be have also published their values and can see that they're quite an all in agreement, which gives us some confidence that we've gone that we've done this the right way.
Sean: So after we've done that, the radium TT three what's next. So the next stage is to determine that. Look at the half lives, make sure these are accurate and precise.
Sean: So if we because these are critical for calculating corrections for in growth. And if we look at the recommended values on the decay data evaluation product.
Sean: We can see we can, we can see that they're not too bad. Well, the authority to sevens. Okay, it's quite precise.
Sean: But it is of course based on one measurement. So it probably needs to be checked again and that measurement was done in the 1960s.
Sean: The radium two three has been based on a number of measurements, but quite a big spread on them so they have quite a high uncertainty and that uncertainty really feeds into the propagation
Sean: The error or uncertainty propagation and therefore we lose precision very very quickly on a primary standard
Sean: So I just want to tell you segue quickly to uncertainties and half life. So when I, when I first started, I was involved in a project to evaluate 69 radionuclides
Sean: For the half life. And when we were doing this, we found that there was quite a skin consistent evaluation or data set. So, and they seem to because it routinely the and there is an underestimation of uncertainties, with many studies on equating the uncertainty of that fit.
Sean: So it is really one we fit we determine the uncertainties with the estimate the uncertainties properly and a paper published recently.
Sean: proposed an uncertainty propagation formula and importantly that identified that the three areas to think about when you're trying to determine your uncertainty. So you have a high frequency medium frequency low frequency so
Sean: The way the low frequency, you're very unlikely to see within your residuals, but they might be there and they might be throwing off your actual the real value. So the analysis of residuals of the fit become key to what you're when you're doing the analysis of half lives.
Sean: So the half life of writing, two, three, we use the ionization chamber which has some long term stability and because it uses a back to back system so uses these two
Sean: These two ionization chambers here, it cancels out the background so reduces the background significantly and it has a good linearity of response.
Sean: For me fit the residual when we make the fit to the data we find that there's a small as an increasing trend in the residuals. As you can see very clearly here.
Sean: And we've looked at that we find that actually there's a there's a range change in the digital volt me to drain the measurements which has caused some non linearity. So, to be honest, which will be changing that to good linear, linear narrative response over the same voltage range.
Sean: So if we take those data points out, we get a new fit and we see that there's no doesn't seem to be any trends in the residuals. This time around, so we now get a final value.
Sean: Where when. Here's an example of uncertainty budget.
Sean: And all the different types of components. And you can see those things like the background and purity and your stability in linear narrative your system that you might not be able to say, and they need to take care of.
Sean: So, in comparison to lecture PTB also released the value or publish the value of the same time. And you can see that were important good agreement.
Sean: And we're all saying agreement with the Kirby value from 1965 so we've reevaluated of the van, the half life value and we have to come up with a value of this based on these three values and the rest of these were rejected for one reason or another.
Sean: So for the half life authority to seven.
Sean: If you look here, we will all of the major previous measurements, apart from this one have all been done by in growth servings in Germany indirectly by engraved of the K progeny and not by the measurement for and 67 directly. So we've that we've
Sean: So we've done this by gamma ray spectrometry to give us a direct measurement and also by an island is ionization chamber which also gives us, which gives us an indirect measurement. So we get a all the decay progeny remove before starting these measurements.
Sean: So for the gamma ray spectrometer mentioned system we we use three regions of interest. So there's 50 K. The 236 Dublin and a 300 kV
Sean: It's not so simple to pick what region of interest, you're going to have because there's not many gamma rays. You can use which have a sufficient intensity on being interfered with by the decay progeny.
Sean: So if you do the fits to all of the measure data.
Sean: This is what we got. And we can see that we there's quite a significant trend in the data here, they sit here and again there's a small trend here doesn't seem to be any in the 300 K v.
Sean: And investigating that we found that there was a problem with the goodness of fit of the net peak areas.
Sean: And it's changing and evolving over time. And this was basically because as you take a portion. You're coming in, you're, you're increasing the container, the content continuum.
Sean: And as the radium to the decay progeny have in some cases of higher energies gamma's with higher intensities. They're changing the content underneath gamma's the cameras were looking at. So we have to
Sean: take account of that and about we kind of estimated about 15 days is about cut off for weather stops becoming a significant problem. So we then end up getting a new new estimation of the heart fi from each of the first tee day sets of the 50 K vanity 36
Sean: So for the ionization chamber, and this is the indirect one we're measuring the some of the response and each radionuclides has a different response. But if we wait for
Sean: Some amount of time. So I think it was about four to six hours, we can assume all the progeny of the radium see three
Sean: Or four. Sorry. All the progeny was sharing the half life of ready until you three so that point and we can assume that was just the two body system instead of having lots and lots of decay progeny. We had to fit.
Sean: So we did that using this equation. And it's quite simple one. But we're decay us function here is to K correcting to the end of the measurement because we can't actually decay. The measurement itself to the beginning of the measurement
Sean: And also as or to discuss briefly a bit in a second, we fixed the half life of the radium or the decay constant, the radium in this fit.
Sean: Because there's a quite strong relationship linear relationship between the thorium and the radium half lives when you're doing these fits. But as we can see, when we did these fits. We can they looked really good and all the residual they don't seem to be any trends within the residuals.
Sean: But I said there's a there is a very strong linear relationship between 30 to seven and right into two three half lives. So within your fit it could easily be and this happened to previous people and they were doing.
Sean: In previous publications. If you could easily end up with your half life fit appear and so you're getting a high rating to do three half life but a low
Sean: 37 half life for the opposite way around. So being aware, the way that the half life because we've used to fix half life and it could change over time with new values coming in and the new evaluations happening we
Sean: We provided a fit or coefficients to be able to change the half life of the forum dependent on if the radium teaching three half life has changed. So you're just giving us a future proof.
Sean: Or MTG seven half life. But that was like gave us a chance to reduce the uncertainty, so you don't have to worry about this big range, you're covering a large range.
Sean: To make sure that we're always encompassing it because we're going to always be moving
Sean: So these are the results of the, the three gamma emissions and then these are two iron chamber samples and like so.
Sean: We didn't respect the three is very consistent again with on chamber, they're consistent as well. And so these the uncertainties on bars on these are just the statistical
Sean: Uncertainties and then what these final results have had all the extra uncertainties applied that the uncorrelated or the correlated uncertainties in in combined in quantity
Sean: So we look at the previous
Sean: Value. So we only have when we read, we ended up having to reject a lot of values are in previous published values and separatists Jordan blank one
Sean: But there was a problem where the uncertainty with very, very precise, but they'd also quoted within their paper that they had a different value.
Sean: And they're two different values didn't agree because the uncertainties were underestimated. So we've and we've we had to improve increase the uncertainty on that value just for this for this evaluation. We can see that light at this point all the values become consistent
Sean: So now we have some branding date half lies.
Sean: The authority, one has changed the numbers. Is it is different numbers significantly different, but the precision is no is a little bit worse, but the radium two to three has changed quite significantly. The precision has got much better.
Sean: And it's
Sean: It. We now have a data, we now have some half lies, which was very comfortable about we can apply within the work we're doing
Sean: So as next. So as we're saying is importance of radio chemistry, being able to remove the progeny effectively and also being able to measure.
Sean: And check that fit efficacy of that separation.
Sean: So we also. So, this problem. The chemical separation has to be very good. It has to be good because we need a time zero from
Sean: Let's close to time separation, because it's not always entirely possible to determined experimentally.
Sean: Especially if you're in a nuclear medicine department where they they have to separate the progeny before creating the drug for they inject into the nation. So they have to
Sean: They don't have that. And they might not have a gamma respect, so they weren't they might be not be able to measure this time zero. And we also need to know the time zero precisely so that we can have a price precise standardization.
Sean: So the right you can have the right chemistry team looked at different
Sean: Chromatography resins or extraction methods.
Sean: So I don't do radio chemistry. So in this case, I'm I don't really know a lot about what I'm talking about. And so they they I, we were able to identify by measuring the time zero of the separation or the effective times zero, because there's always that the TV. The TV resin had the most
Sean: Seem to be the best removing the decay progeny, so half an ounce. Okay, it's not it's not it's not a big deal for what we were doing, but
Sean: When we went to got to, got to the actual proper standardization that we reported and the radio chemists added a vacuum box to the method. So, where they said the end of separation was nine o'clock and leisure time zero with something only about three minutes.
Sean: Prior to that end of separation and we're able to do measure that with excellent decision about one minute. So at this point.
Sean: This is this is excellent. Use this is a read this would be a really good method for using in nuclear medicine departments.
Sean: So civilization authority seven was carried out by two primary methods for pilot percent gamma Clinton's campaign for point alpha, they could sink counseling and we use to confirmatory engrave techniques using gamma ray spectrometer Indian ization chamber.
Sean: So just to show you the corrections worked. You can see that this was the count right on the left hand side, you can see the count rate was increasing.
Sean: That we observe camera was increasing the one we applied the corrections. You can see they've become quite consistent over 500 hours and this the red the solid red line is the reported activity and these are, this is a standard uncertainty.
Sean: So the problem with the absolutely gamma ray emission intensities. So why we can't, can we can confirm or support the activity of the promise standard just using the thorium emission intensities well as 11% 11% spread in the activities to turn by the main gamma emissions.
Sean: And when you take the Weighted Mean it's a minus 3.4% difference also it's incredibly precise because it has an 8.5% uncertainty on the normalization scaling factor quoted in the end staff data set, so we can make some significant improvements using the primary standard
Sean: But for the use of confirming the primary standard we we use the accuracy of
Sean: precision of the rate in 23 and Radeon to on nine gamma emissions that we've been that we've mentioned previously, to be able to to to to be able to
Sean: Provide a more accurate activity answer them. He is the intensities of the absolutely mentioned intensities as way to mean that the MPL nest and PTV values.
Sean: And
Sean: We can determine the activity that started measurement using this equation. So this, this is the important part. So we need to be able to correct for the growth of radium from Florence at seven during the course of the measurement. So this is the equation down here.
Sean: And from that, when we've made all those corrections, we get this nice data set here which we can fit using this Bateman equation and we only need to vary the activity authority of the time zero.
Sean: And we can see that this works very well and we get a nice set of residuals, and every look at all for gamma emissions, we get a nice consistent set of data.
Sean: So overall, we get a nice if you look at all the two primary standardization techniques and the to engrave techniques we get a really nice consistent data sets data set with these two confirming very nicely. The primary standardization techniques.
Sean: One source of controversy during our review in the papers being reviewed was the review didn't like that the uncertainty in the gamma spec was resolved was much less was lower than everything else.
Sean: This wasn't this wasn't the best. It was just, we have a problem. We had a problem on picking the correlations in the absolute mission intensity between the MPL nest and PTV absolutely gamma ray emissions.
Sean: So, for example, real will probably using the same radionuclides and gamma emission probabilities for determining our efficiency.
Sean: So that leads us on to measuring the absolutely gamma ray emission intensities. So the rates were calculated using this equation. And again, we have to make corrections for the growth
Sean: Of the decay approach and me and this is going to follow through, where this equals and D, which is this this formula here, which is that the total count rate that we would have expected to see.
Sean: Based on the growth of the K project and then you can take the weighted mean of all of the rates for a particular gamma energy and just divided by the activity and efficiency. I just gives us the absolute intensity
Sean: So this will end in the end of the day we mentioned, we managed to measure 70 gamma rays. We were only able to do this with singles with a single Gannon specs. There's no coincidence can being able to differentiate between the tablets for using to get and coincidences.
Sean: So we've had to report those as tablets. So, in future, we're going to have to go back with the intended go back and solve that, with the acquaintance set up in future.
Sean: If we just look at the 236 kV intensity. So we look at the gamma quite by n staff. We get 12.9 and if you see the, the end of the MPL versus value. We've determined is 3.3% lower than any staff, but most
Sean: Massively 20 times more precise and a part of the problem of that episode season of the original value is because we don't have the decay schemes not well known as actually some problems in it.
Sean: And it's quite as a very complex the case.
Sean: So we can just compare quickly to the literature. And so there's only really there's been three previous
Sean: set of values reported and in most cases, it looks like they're all in relatively good agreement with Kai's reduce code squares of almost one
Sean: But actually that's Jesus just very high uncertainties on these measurements. So we were looking at order of magnitude more precision than previous work.
Sean: So where the outcomes of this. So the FDA and a year for us have approved traceability for the clinical studies authority to seven to the primary standard MPL which is a bit of a first because
Sean: They usually insist that the traceability has to be to nest and so they've signed now phase one clinical trials and are proceeding.
Sean: And people respond to you look at investigate quantitative model medical imaging using the third entity seven and using the gamma emissions. The we've presented here.
Sean: So in summary, we've developed traceability for 30 732 liquids installation techniques we've developed effective radio chemistry.
Sean: New precise measurements of the half lives made for 37 radium 33 and later 11 which I'm discussed in this presentation and you precise absolutely mission and tendencies for
Sean: Progeny derived from the primary standard and there's still work to be done on the case game. So just been been sent. We've just collected some more data based on some for him to do seven data using a system that looks like this picture in the corner.
Sean: And it wouldn't be fair, not to give credit to all the people who have been involved in this work and they've all made massive contributions to everything that's occurred here.
Sean: And thank you very much for your time.
James Smallcombe: Thank you very much. So great, and I will just say I'm Sorry for the interruption. And again,
James Smallcombe: That's
James Smallcombe: The people listening on the recording for the fact I missed off the first few slides.
James Smallcombe: I thought it was very good tool, even for those people that missed the first few slides. So now we will open the floor up to questions. So as I said at the start.
James Smallcombe: If you go into the participants menu. There's a little raised hand icon and that'll tell us you put a question. I think we've already got a few digital claps good
James Smallcombe: Again, if you want to go into the chat and type your questions in the chat, then we'll ask them for you.
James Smallcombe: While people are having a think I will just so you mentioned you want to go back and do a coincidence measurement is already set up for that. The MPL or will you be building well
Sean: Yeah, no, we just say that picture is essentially a solid works of something we just built
Sean: So we've actually collected later data.
Sean: I just now have to do the analysis.
James Smallcombe: I also
Sean: Is there. I just, I'm
James Smallcombe: Just check. I still don't see any hands just yet. Oh, there we go. Fill up please unmute yourself and go ahead with your question.
Philip Adsley: Hello, I have a very basic question. I think it was something that I missed, but it might be early enough that it was before the recording started so it might be useful. And how do you make these
Philip Adsley: The things like the
Philip Adsley: And various other things because I know that in some cases, is it just chemical extraction from decay products or or is it something else.
Sean: Yeah, so we so we got so we get sent authoritative seven because it's got a long enough, half life. It can be
Philip Adsley: Shipped
Sean: Us, but I know the buyer have a large actin entity seven source.
Sean: So they will do the separation and then I'll send it to us.
Philip Adsley: Okay, so the continuum is
Sean: Yes, I like 10am is the
Philip Adsley: Out of
Sean: The yeah so axiom 37 is that is the precursor to all of them, because as a 20.7 year half life.
Sean: So they have a large sorts of activity seven. I mean, I went around scrounging all of it out there in the beginning.
Patrick Regan: They also do a I think I've also got a radium to 26 yea.
Patrick Regan: Or so sorts of the do neutron capture on
Sean: Oh yeah, you can you can definitely do on a tomcat from right into the sex is a really good method.
Patrick Regan: Okay. Do we have any other questions.
James Smallcombe: I have one more. So this is going about the radio chemistry with fewer certainty. When the expert on but I'm not either, which is why it's a question.
James Smallcombe: Could you just briefly go back over the meaning of this one minute offset on the the t zero. And what that means. With respect to the radio chemistry.
Sean: Jimmy the time's arrow here.
James Smallcombe: Yeah yeah
Sean: Okay, so yeah, so
Sean: Sorry. So the end of so so that is the measure time zero, where we've done a we've measured it by gamma spec.
Sean: So obviously there will be an uncertainty on the efficiency and uncertainty in the gamma emissions so that that becomes the uncertainty on the measured time zero.
Sean: So that's, that's not actually an uncertainty on the separation. So when you the chemical separation. They don't actually know when it's been separated
Sean: If you know what I mean. So, over a period of time, or it could happen. It's a shame because I think they do over about 15 minutes or 30 minutes so
Sean: It's a gradual thing over time. So this is more just an effective times there right but it happens to be very close to the end of separation. Oh, thank you.
James Smallcombe: A question in the chat now so jack Henderson wants to know, would there be merit in reporting the full covariance or correlation matrices, especially for the more correlated decays EG, the two to three radium 37 thorium.
James Smallcombe: And more complicated.
Sean: When we have, yes. So we have published the covariance matrix is
Sean: There in the papers. So between the main gamma emission says a covert there's a yeah correlation matrix between
James Smallcombe: So I guess the question is their marriages. Yes, it's been done because
Sean: Yeah, that's an excellent idea.
Sean: And more and more minimized and everybody else should do it, but nobody else does. No.
Slavery.
James Smallcombe: Do we have any other questions, and that was it.
James Smallcombe: I don't see any
James Smallcombe: If I'm missing you because sometimes the system plays up or you don't have the raise hand icon. Please just do go ahead and unmute yourself now.
Of the one is we will move on.
James Smallcombe: Now, I think that's it. So I should say thank you very much, Sean. That was great.
James Smallcombe: And thank you everybody else for joining us before I let you go. I will just get my usual plug for the upcoming seminars, so
James Smallcombe: This Wednesday. We've got another one of the UK student virtual seminars and that's what are the other address hosted by University of Manchester.
James Smallcombe: This week, we've got Caroline Holroyd from Lancaster, who's gonna be talking to us about composition sensitive neutron detection by pulse analysis. So,
James Smallcombe: Do come and join and encourage your students to come and support that peer on Wednesday.
James Smallcombe: After the plenary sessions will be back here. Same time next week when we've got Jenna Wilson from Louisiana State and have on National Poetry, who's gonna be talking to us about studying each decade neutrino.
James Smallcombe: Neutron emissions with recoil and spectroscopy. So that's again Monday 3pm PST so please come back and join us for those, but one final. Thank you very much to Sean and thank you very much to everyone for joining us and have a good week.