HERMES was an experiment conducted using the HERA particle accelerator located at the German national laboratory

DESY The Deutsches Elektronen-Synchrotron (English ''German Electron Synchrotron''), commonly referred to by the abbreviation DESY, is a national research center in Germany. It operates particle accelerators used to investigate the structure of matt ...

Hamburg (male), (female) en, Hamburger(s), Hamburgian(s) , timezone1 = Central (CET) , utc_offset1 = +1 , timezone1_DST = Central (CEST) , utc_offset1_DST = +2 , postal ...

. The experiment's goal was to investigate the

quark A quark () is a type of elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. All commonly o ...

gluon A gluon ( ) is an elementary particle that acts as the exchange particle (or gauge boson) for the strong force between quarks. It is analogous to the exchange of photons in the electromagnetic force between two charged particles. Gluons bind q ...

structure of

matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic partic ...

by examining how a nucleon's constituents affect its spin. It later developed into a pioneering experiment for measuring generalised parton parton distributions and a general-purpose experiment for the study of

QCD In theoretical physics, quantum chromodynamics (QCD) is the theory of the strong interaction between quarks mediated by gluons. Quarks are fundamental particles that make up composite hadrons such as the proton, neutron and pion. QCD is a type o ...

processes. HERMES completed its first run between 1995 and 2000, and a second run began in 2001 and ended during the summer of 2007. HERMES was conducted by

scientist A scientist is a person who conducts Scientific method, scientific research to advance knowledge in an Branches of science, area of the natural sciences. In classical antiquity, there was no real ancient analog of a modern scientist. Instead, ...

s from more than 13 countries.

Method

Polarized electrons are fired at polarized gas targets. The virtual photon emitted by the electron was also polarized and sought out quarks of spin in the opposite direction as the photon. The asymmetry of ejected quarks was determined to deduce the net polarisation of the quarks.

UGFS

The unpolarized gas feed system (UGFS) was used for non polarized "end of fill" or heavy target running before the polarized target was removed in 2003. Afterwards the UGFS supplied the target gasses in the new detector configuration.

References

HERMES

* ttp://nuclear.gla.ac.uk/~protopop/teaching/gui/ http://nuclear.gla.ac.uk/~protopop/teaching/gui/

External links

HERMES experiment
record on

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Particle experiments {{accelerator-stub

Method

UGFS

See also

References

External links