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<p class="MsoNormal"><span lang="EN-US">Colloquium with Prof. Lars Eklund (CERN) and Stan de Lange (ARCNL)
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span lang="en-NL">Walk-in Pizza:</span></b><span lang="en-NL">
<b>12:15 - 12:30</b><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US">12:30 - 12:50 - Stan de Lange, PhD candidate, Nanolitography – ARCNL</span></b><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><b><i><span lang="EN-US">Properties of tin plasmas generated by 2
</span>μ</i></b><b><i><span lang="EN-US">m-wavelength laser pulses<o:p></o:p></span></i></b></p>
<p class="MsoNormal"><b><i><span lang="EN-US"><o:p> </o:p></span></i></b></p>
<p class="MsoNormal"><span lang="EN-US"> <b><u>Abstract:</u> </b>The computer chips that form the cornerstone of modern society are produced in a process called nanolithography. To accurately print their nanometer-scale features, one needs extreme ultraviolet
(EUV) light. This light is harvested from a tin plasma, created by firing laser pulses on tin microdroplets at a dizzying rate of 50 000 shots per second. Currently, this is a multi-step process: first a ‘pre-pulse’ squashes the droplet into a thin pancake,
and then a CO<sub>2</sub> ‘main pulse’ laser creates the plasma.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I research the generation of EUV with a new type of Tm:YLF laser, which can sustain pulses long enough to fully vaporize the tin droplets without the use of a pre-pulse, and thus obtain more EUV per shot. In two papers,
we used the radiation-hydrodynamics code RALEF-2D to study the properties of this ‘main pulse only’ scheme: in the first, we visualize the EUV-emitting space, study the motion of the droplet as it is being vaporized, and calculate the EUV yield. In the second,
we look at the properties of the highly energetic (and damaging) ions that are emitted from the tin plasma; specifically, we study the ion spectrum and all its features.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US">12:50 -13:45 - Prof. Lars Eklund, Uppsala Universitet and CERN</span></b><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><b><i><span lang="EN-US">Antimatter - an almost perfect mirror image of matter<o:p></o:p></span></i></b></p>
<p class="MsoNormal"><i><span lang="EN-US"><o:p> </o:p></span></i></p>
<p class="MsoNormal"><b><span lang="EN-US">Abstract: </span></b><span lang="EN-US">The existence of antimatter was predicted from combining two principles of physics, and antimatter has since been observed and studied in radioactive decays and cosmic rays.
In fact, antimatter is a complete mirror image of matter, where very particle has an antiparticle. Antiprotons and positrons can be produced at accelerator labs and combined into anti-hydrogen, where experiments at CERN in Geneva have shown that they have
the same properties as their matter counterparts.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">However, matter is much more abundant than antimatter in our universe, which from cosmological arguments indicate that some process that favours matter over antimatter must exist. The standard model of particle physics
provides such mechanisms, which can be studied in decays of particles produced at high-energy colliders. The leading experiment for such studies is the LHCb experiment at CERN which has measured the matter-antimatter asymmetry in many decay processes. The
measurements are so far consistent with the predictions of the standard model, but not consistent with a matter-dominated universe.
</span>This contradiction is an intriguing open question in physics.<o:p></o:p></p>
<p class="MsoNormal"><span lang="en-NL"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="en-NL"><a href="https://vu.nl/en/events/2025/physics-colloquium-november-2025">https://vu.nl/en/events/2025/physics-colloquium-november-2025</a><o:p></o:p></span></p>
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