Density effect corrections below 1 keV

[Jaap1957]

Daar forum,

As Mr Tessier shows in #826, the "AE" lower limit has a not negligible influence on energy spectrum results.

Part of this is due to the ESTAR table which lower end is 1 keV.
Here the first few points of this table, (i added (0,0) )

It gives me the strong impression that a straight line from the lowest point to (0,0) would be a good extrapolation.

Would it be an idea to just extrapolate the ESTAR density correction factor from the lowest point to (0,0) ? That would remove 1 of the 4 low energy limits. I did not study this extensively but you are the experts, and maybe this is already a very old idea.

Nice code !

[ftessier]

I presume that EGSnrc indeed interpolates to zero (I would have to check in detail) to calculate the restricted stopping power between 0 and 1 keV (or more generally 0 to ae). But at any rate, as you can see in your graph at low energy the the density effect correction is pretty much insignificant; it is a relativistic effect.

The impact of ae on the spectrum is not related to the density effect correction (or lack of data point below 1 keV); it is simply due to the fact that secondary electrons below ae are never generated in the in the first place!

[Jaap1957]

Maybe just discaard this idea then.

…

________________________________ From: Frederic Tessier ***@***.***> Sent: Thursday, January 27, 2022 14:19 To: nrc-cnrc/EGSnrc ***@***.***> Cc: Mulder, Jaap ***@***.***>; Author ***@***.***> Subject: Re: [nrc-cnrc/EGSnrc] Density effect corrections below 1 keV (Discussion #834) CAUTION: This email originated from outside of Thermo Fisher Scientific. If you believe it to be suspicious, report using the Report Phish button in Outlook or send to ***@***.*** I presume that EGSnrc indeed interpolates to zero (I would have to check in detail) to calculate the restricted stopping power between 0 and 1 keV (or more generally 0 to ae). But at any rate, as you can see in your graph at low energy the the density effect correction is pretty much insignificant; it is a relativistic effect. The impact of ae on the spectrum is not related to the density effect correction; it is simply due to the fact that secondary electrons below ae are never generated in the in the first place! — Reply to this email directly, view it on GitHub<https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_nrc-2Dcnrc_EGSnrc_discussions_834-23discussioncomment-2D2058640&d=DwMCaQ&c=q6k2DsTcEGCcCb_WtVSz6hhIl8hvYssy7sH8ZwfbbKU&r=RuHtnlWlvUXLnyJh7OQlBzHRAiqrOJNsNVOZ5u11DCc&m=soaXHe7LbZmEoqQVYrpHczZ5k3erQnDeQ7kJmAcHLSvtuXQMCbEnMlJ5L1fTFOM0&s=-eeZ7MgqliCSEoz5fyB4oNkPTG1PCZcpH2d1W8CZHcQ&e=>, or unsubscribe<https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_notifications_unsubscribe-2Dauth_AXDN3D2M5AO5CDDZLX76AKLUYFA6TANCNFSM5M5OCAGA&d=DwMCaQ&c=q6k2DsTcEGCcCb_WtVSz6hhIl8hvYssy7sH8ZwfbbKU&r=RuHtnlWlvUXLnyJh7OQlBzHRAiqrOJNsNVOZ5u11DCc&m=soaXHe7LbZmEoqQVYrpHczZ5k3erQnDeQ7kJmAcHLSvtuXQMCbEnMlJ5L1fTFOM0&s=a3e6AOO12isQrXsahv-KXa--WKmZqClYAkqhGE2HNW0&e=>. Triage notifications on the go with GitHub Mobile for iOS<https://urldefense.proofpoint.com/v2/url?u=https-3A__apps.apple.com_app_apple-2Dstore_id1477376905-3Fct-3Dnotification-2Demail-26mt-3D8-26pt-3D524675&d=DwMCaQ&c=q6k2DsTcEGCcCb_WtVSz6hhIl8hvYssy7sH8ZwfbbKU&r=RuHtnlWlvUXLnyJh7OQlBzHRAiqrOJNsNVOZ5u11DCc&m=soaXHe7LbZmEoqQVYrpHczZ5k3erQnDeQ7kJmAcHLSvtuXQMCbEnMlJ5L1fTFOM0&s=ompHVeAWJN9JveWykFyG8cjyus-xvFmCOdmteyf0Cgg&e=> or Android<https://urldefense.proofpoint.com/v2/url?u=https-3A__play.google.com_store_apps_details-3Fid-3Dcom.github.android-26referrer-3Dutm-5Fcampaign-253Dnotification-2Demail-2526utm-5Fmedium-253Demail-2526utm-5Fsource-253Dgithub&d=DwMCaQ&c=q6k2DsTcEGCcCb_WtVSz6hhIl8hvYssy7sH8ZwfbbKU&r=RuHtnlWlvUXLnyJh7OQlBzHRAiqrOJNsNVOZ5u11DCc&m=soaXHe7LbZmEoqQVYrpHczZ5k3erQnDeQ7kJmAcHLSvtuXQMCbEnMlJ5L1fTFOM0&s=uZb_2VgCaxVVSaBkURessp6ZixIYZkwdpmJ4MgOAw88&e=>. You are receiving this because you authored the thread.Message ID: ***@***.***>