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accelerator/notes
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29
accelerator/notes
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notes:
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from program Sim NRA
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kinematic factor @ 2.000 ±0.001 MeV
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150 degrees
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Cu: 1885.05 ± 0.01
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Si: 1749.21 ± 0.01
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can find a ratio between the lithium and flourine cross-sections
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taking the ratio of the yields and cross-sections allows things like target thickness to drop out
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what you're after: the yield and the cross-section are basically proportional to each other
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in lab write-up
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A big danger:
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Flourine curve very sensitive to different in energy of about .1, so this could change your ratio greatly
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this would be a systematic error that caused an energy shift to explain wrong values
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102
notes.R
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102
notes.R
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plot(y,xlab="Channel",ylab="Count",lwd=4,pch="-")
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lines(v[3]*exp(-1/2*(x-v[1])^2/v[2]^2),col=2,lwd=1.4)
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abline(v = 7813.63,col=4,lwd=1)
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axis(3,at=7813.63,"5.486 MeV")
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dev.print(pdf,"../report/calibration.pdf")
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Alpha Activity
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plot(data_4_2,xlab="Energy [MeV]",ylab="Count [Alpha Particles]",pch=".")
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minor.tick(nx=5,ny=2)
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abline(v = 5.631,col=2,lwd=1)
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axis(3,at=5.631,"5.6")
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abline(v = 5.323,col=2,lwd=1)
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axis(3,at=5.323,"5.3")
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dev.print(pdf,"../report/activity.pdf")
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For Gaussian Fits:
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─────────────
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x <- seq_along(y)
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f <- function(par)
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{
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m <- par[1]
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sd <- par[2]
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k <- par[3]
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rhat <- k * exp(-0.5 * ((x - m)/sd)^2)
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sum((y - rhat)^2)
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}
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optim(c(15, 2, 1), f, method="BFGS", control=list(reltol=1e-9))
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─────────────
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I propose to use non-linear least squares for this analysis.
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# First present the data in a data-frame
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tab <- data.frame(x=seq_along(y), y=y)
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#Apply function nls
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(res <- nls( y ~ k*exp(-1/2*(x-mu)^2/sigma^2), start=c(mu=7500,sigma=50,k=1) , data = tab))
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And from the output, I was able to obtain the following fitted "Gaussian curve":
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v <- summary(res)$parameters[,"Estimate"]
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plot(y~x, data=tab)
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plot(function(x) v[3]*exp(-1/2*(x-v[1])^2/v[2]^2),col=2,add=T,xlim=range(tab$x) )
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Mirror Gumbel Distribution:
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(res <- nls( y ~ (1/beta)*exp((x-alpha)/beta - exp((x - alpha)/beta)), data=cal,start=c(alpha=7800,beta=1),control=list(minFactor=1/50000,maxiter=1000)))
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v <- summary(res)$parameters[,"Estimate"]
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plot(function(x) (1/v[2])*exp((x-v[1])/v[2] - exp((x - v[1])/v[2])),col=2,add=T,xlim=range(tab$x))
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──────────────────────────────────────────────────────────────────────────
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─────────────
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File writing
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write(x, file = "data",
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ncolumns = if(is.character(x)) 1 else 5,
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append = FALSE, sep = " ")
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dev.print(pdf,'filename.pdf')
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──────────────────────────────────────────────────────────────────────────
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─────────────
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Axis Formatting
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# Add minor tick marks
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library(Hmisc)
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minor.tick(nx=n, ny=n, tick.ratio=n)
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──────────────────────────────────────────────────────────────────────────
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─────────────
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Importing CSV
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