Basically, light has a property to undergo what's called diffraction: shine a laser beam on a grated piece of plastic and beam will split into an uneven number of new beams. Using this pattern and some trigonometry you can calculate the wavelength of light if you know how fine the grating is and the angle between beams. This works only when wavelength is a few times smaller than the grating size.

Now, the important bit is that atoms in crystal sort of work like grating. Light reflects from different layers of atoms differently and this forms the same diffraction pattern. Since the distance between atomic layers determines the structure of the crystal, we can now measure it using light and some math called Bragg's law. The only thing we need is a light source with fixed, well-known and very small wavelength. Now, the "grating" in our case is approximately 2-4*10^-10 m, or 2-5 angstrem.

Conveniently, metallic anode, when put in a vacuum and under high voltage, emits high energy photones, generally of a fixed wavelength, corresponding to the valent electron's excited state. And if we use copper, this wavelength is roughly 1.51 angstrem, which is about what we need.

Now that all elements are in place, we just need to build a complex machinery that will hold our sample, put a piece of copper under a few kilovolts, cool it down simultaneously, while also rotating a detector to capture light intensities under a range of angles. Different lattices will give different diffraction patterns, and one can be calculated from another.

And this is more or less how x-ray diffraction works.

#qotojournal #science #xrd #materialsciences

**Paul Sutton** @zleap@social.cleverlibre.org · Oct 12, 2021, 17:39

**Paul Sutton** @zleap@social.cleverlibre.org · Oct 12, 2021, 17:39

Oct 12, 2021, 17:39

Paul Sutton @zleap@social.cleverlibre.org

I noticed the other day that my netbook screen was slightly odd on one side of the display. I see this as a sign of impending screen doom.

As I have another netbook (same model) lI am going to just swap the HDD and memory over to the netbook (same model netbook).

Linux systems seem to be happy with this happening, you can't do it with windows as it figures out it is different hardware (even if it is an identical make / model).

So have something to do now before the England vs Hungary game.

**Paul Sutton** @zleap@social.cleverlibre.org · Oct 12, 2021, 17:36

**Paul Sutton** @zleap@social.cleverlibre.org · Oct 12, 2021, 17:36

Oct 12, 2021, 17:36

Paul Sutton @zleap@social.cleverlibre.org

I have a meeting with the Torbay Geopark education group tomorrow so am taking some of the info flyers for the Fediverse, so I have something to explain what Mastodon is all about.

Torbay is a UNESCO geopark due to the geological importance of the area.

**Paul Sutton** @zleap@social.cleverlibre.org · Oct 12, 2021, 17:31

**Paul Sutton** @zleap@social.cleverlibre.org · Oct 12, 2021, 17:31

Oct 12, 2021, 17:31

Paul Sutton @zleap@social.cleverlibre.org

We now have a new TOY (well piece of training kit) at the Torbay Trojans, A JUGS machine.

This allows a ball to be propelled forward to simulate a Quaterback passing the ball or with the other attachment, allows a punt to be simulated

Kinda fun, but also pretty powerful.

https://jugssports.com/other-team-sports/football/

#Sport #Football #JugsMachine #AmericanFootball #Trojans

**Paul Sutton** @zleap@social.cleverlibre.org · Oct 12, 2021, 17:24

**Paul Sutton** @zleap@social.cleverlibre.org · Oct 12, 2021, 17:24

Oct 12, 2021, 17:24

Paul Sutton @zleap@social.cleverlibre.org

I have created a small display at Paignton Library to promote STEM the Nobel prize info graphics tie to last weeks awards.

https://www.torbaylibraries.org.uk/web/arena/paigntonlibrary

**Paul Sutton** · Oct 11, 2021, 19:11

Paul Sutton boosted

**Tactical Tech ✅** @info_activism@mastodon.cc · Oct 11, 2021, 19:11

Oct 11, 2021, 19:11

Tactical Tech ✅ @info_activism@mastodon.cc

Leaked Apple Training Videos Show How It Undermines Third-Party Repair https://www.vice.com/en/article/5dbv83/leaked-apple-training-videos-show-how-it-undermines-third-party-repair

**Paul Sutton** · Oct 11, 2021, 17:20

Paul Sutton boosted

**Electronic Frontier Foundation** @eff@mastodon.social · Oct 11, 2021, 17:20

Oct 11, 2021, 17:20

Electronic Frontier Foundation @eff@mastodon.social

We wish Apple had listened to more voices before deciding to scan our phones. We’ve brought some groups together that need to be heard. Join us on Oct. 12: https://www.eff.org/event/perspectives-encryption-and-child-safety

**Paul Sutton** @zleap@social.cleverlibre.org · Oct 11, 2021, 17:33

**Paul Sutton** @zleap@social.cleverlibre.org · Oct 11, 2021, 17:33

Oct 11, 2021, 17:33

Paul Sutton @zleap@social.cleverlibre.org

@sfcamp & @fsfe

I have tried to share info on the software freedom camp and Youth hacking for freedom evnts. with various people locally in Torbay, Devon,

It seems people locally are not capable of reading or replying to e-mail, even when I have dropped in to their office, asked about sending people stuff and then sending, that way they know it is from me and not getting lost in their spam folder.

I put the following flyer together, very quickly to help me over the weekend at least give the info out and start the conversation.

I am at Code Club on Saturday so hopefully will have more luck directly talking to people.