# A visit to DESY To photograph black holes (SL), it requires radio telescopes. However, to track them down from Earth, gamma telescopes are needed, because the biggest obstacle is and remains the atmosphere.

For those telescopes, objects like SL do not appear as single punctiform light sources but as several weaker light sources. This is due to the over 100km of our protective layer, which has the refraction of light. The exact location can be reconstructed using telescopes about 11km in diameter by combining the received signals.

What brings us to the actual occasion: I was visiting the Helmholtz Association in Hamburg. After an introductory lecture, we were shown in a tour the eponymous DESY (German electron synchrotron). This is one of several particle accelerators on the entire area outside the city.

It is the largest active ring accelerator with 2km circumference, because HERA (6.3km) is now switched off. In addition, the site has more linear accelerators and synchrotrons.

Synchrotrons can be used to detect so-called synchrotron radiation. That is a radiation, which emit particles only at extremely high speeds and thus lose energy. In general, the following applies: $\Delta E=\frac{(Ze)^2* \beta^3 * \gamma^4} {\epsilon _0 * 3R}$ $\Delta E=\frac{(Ze)^2* \beta^3 * \gamma^4} {\epsilon _0 * 3R}$With AE → synchrotron energy; Z → ordinal number; eelementary charge; ε₀ electrical field constant; Rsynchrotron radius; βv / c
y → Lorentz factor = E / m * c²

For electrons with very low mass and accelerated to almost the speed of light (β ≈1) this means: $\Delta E=\frac{(Ze)^2*E^4} {\epsilon _0 * 3R * (mc^2)^4}$ $\Delta E=\frac{(Ze)^2*E^4} {\epsilon _0 * 3R * (mc^2)^4}$
This means, for example, that the emitted energy increases by a factor of 2⁴ when the mass is halved.

For protons, the energy is smaller by a factor of 10¹² and is thus negligible. Nevertheless, HERA has a (test) route for both electrons and protons.

The next aspect would be the beam time: This is only possible by building a measurement, which can take up to one day. She herself describes the subsequent measurement time, usually several hours, so that a decent number of emerge emissions can be analyzed. However, this is far more lucrative, since to capture a comparable amount of radiation with the Hubble Space Telescope would result in significantly higher costs.