Re: Si pin xrf ..1st go
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taray singh
Dud remarkably efficient source / geometry set up... I am not sure but maybe this is why. ?I am using a slightly convex ludlum collimator lead disc ? 9 Am241 exciter are glued on? the outer edge? ?in a circular fashion producing a divergent beam. This minimizes primary? beam entry through? the central window Divergent beam? also minimizes scatter from interactions? with sample LOw Z organic samples like plastics ,cellulose? and organic compounds are Compton producing The detector? cap window is about half inch away from the collimator disc? aperture This acts as a partial collimator preventing unwanted ray entering EVen the sample has to a be about half inch away Too close,the divergent beam yields poor results I rely mainly on the polychromatic gamma rays and less on the alpha radiation? from Am241 This detector warms up about 1 to 4 degrees? Celsius on usage In my experience placing blocks of metal on 1 or? both sides? helps cooling? ?significantly Do not place anything on top because any vibration is gonna disturb the spectrum Extra cooling will improve performance I reset my? max range settings? to about 80 kev. 2048 channels limits my range? preference. 2048? is a good compromise between 1024 and 4096?? I repeated the meteorite? test with this new settings Nickel L alpha? peak appeared within 15 mins and beta peak? is coming in slowly? Proper setup can yield faster results...I? think.. I had bad experience earlier doing long counts I accidentally exit? the? programme after pulling out the? usb Later on reconnecting the Dppmca refused to communicate with the detector Forced to shut down detector and restart windows Besides also having some minor software and hardware issues Otherwise this si pin is really helpful. Pics are for setup and spectrum files Taray ? ?
On Saturday, October 24, 2020, 12:54:29 AM GMT+8, Dude <dfemer@...> wrote:
Taray, Looks good with the 2048. There are two things that could be done for your setup. The first is the count time, you really need much more count time to resolve things especially close lines and the confirming weaker La lines. The other adjustment you need to do is reduce the energy range which is extending right now up to 116.9 keV. With an Am source at 59 keV you¡¯ll not fluoresce anything above 60 keV and very weakly at 59 due to the drop in efficiency of the detector above 30 keV. You¡¯ll want to set your maximum energy range to 64 keV, that will allow you to use the Am 59.5 keV peak to calibrate on and will maximize your energy range of interest. To do that you¡¯ll count the Am source and set the gain so that peak occur at channel 1904. From what your gain is set at now it will be about half that gain setting. Fine tune the gain until the 59.5 peak sits at channel 1904. That gives you 0.03125 keV/ch or 32 channels / keV with a maximum energy range of 64 keV. The other thing we are all in awe about is the remarkably efficient source / geometry set up you have. We see very little 59 backscatter, no Np and yet peaks coming up with very short counts. How about a write up and some pictures of your source set up and the geometry you are using. Dud ? ? ? From: [email protected]
[mailto:[email protected]] On Behalf Of taray singh via groups.io
Sent: Friday, October 23, 2020 6:35 AM To: [email protected] Subject: Re: [XRF] Si pin xrf ..1st go ? Dud? |
