[Halld-tagger] SiPM radiation hardness test

[Richard Jones]

  Yi,

Thank you for these results.  I need some time to convert them into tagger performance figures in my simulation (time resolution and efficiency).  Let's stop the irradiation at this point and watch the dark current over the next several weeks.  There may be more than one time constant in the recovery curve.

-Richard J.


On 9/7/2010 10:14 PM, Yi Qiang wrote:
>    Hi Igor and Richard,
>
> Here I attached some plots showing the results of the radiation hardness
> test of the 2x2 SiPM from UConn.
>
> All the results are shown with bias voltage of 36.3 V on the SiPM. And
> here are some descriptions for the plots:
>
> 1. damage.png/eps show the dark current increase as a function of dose
>
> 2. recovery.png/eps show the recovery curve of the dark current as a
> function of time, more time is needed to get a more precise base line.
>
> 3. VI_curve.png/eps show VI curves at different stages of irradiation
> and recovery, all these curves have a very similar exponential behavior
> close to the working voltage and I actually used this slope to correct
> the data in case I was not applying 36.3 V on the SiPM.
>
> 4. signal_pedestal.eps/C/png are ADC histograms w/o or w/ light input,
> left column is for pedestal runs and right column is for runs with
> signal. The ADC gate is 200 ns. Even we could not see the individual
> photon peaks with such a large gate, from the difference of pedestal and
> signal, we can tell that the product of gain and PDE didn't change much,
> within 10%. So the increase of dark current should be a good indication
> of the change of the noise level. Since I also used flash ADC to take
> the raw data with a window size of 280 ns, ADC spectra with narrower
> gate length can be generated later on if necessary.
>
> Cheers,
> Yi
>
> ------------------------------------------------------------
> Yi Qiang      Thomas Jefferson National Accelerator Facility
> Staff Scientist                12000 Jefferson Lab 12_3/F351
> yqiang at jlab.org                       Newport News, VA 23606
> Phone:(757)269-7237                        Fax:(757)269-6331
> http://www.jlab.org/~yqiang/web
> ------------------------------------------------------------
>
>

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