Different Crystals

[gerhard]

Good evening dear members,
I have a problem showing one of my crystals. It is a 2,5 x2,5 inch NaI crystal. It shows some distortion on the base in PRA 15 but not in Theremino MCA.

C137_2,5_021116.png

C137_2,5.png

than with a selfbuilt 18x40mm NAI Detector

C137_CA_011116.jpg

C137_CA.png

than with the factory built GS 1,5x1,5 inch System

C137_GS_021116.jpg

C137_GSa.png

and at last with my new RAP47 1mm CsI detector

C137_Rap47a_031116.png

So, i am new, please can You make any comments,what You see thats wrong ?
Esp. on the 2,5 inch System
Resolution about +- 8 %

thank You

[Sesselmann]

Not exactly sure what distortion you are referring to, is it the sharp edge on the right shoulder?

If so can you check if your Tolerance correction is set to Zero in Data Acquisition and Analysis?

C137_2%2C5_021116.png

[gerhard]

Thank You, Mr. Sesselmann, for help.
I use PRA 15 and Tolerance Threshold is 5, Correction is 0 and Boost gain 1.
No shielding at all. I dont have one.
Yes, the right, but also the left shoulder. This peak seems on the base not symmetrical and especially on the left shoulder. It deviates to the left.
I have read in Your Forum,that maybe, the crystal is a little wet, than the left schoulder ist going more to the left. I think it was luuk ?
But, maybe, i am wrong and missunderstood something.
I use for C137 this old spark gap, 4 together in a housing of plastik.
But, if You think, this spectrums are more or less ok, so please,tell me.

With best regards
gerhard