# Mainz 2012 – wissenschaftliches Programm

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# HK: Fachverband Physik der Hadronen und Kerne

## HK 65: Beschleuniger

### HK 65.4: Vortrag

### Freitag, 23. März 2012, 15:30–15:45, P 3

**Nondestructive monitoring of proton beam emittance** — Roman Dzhygadlo, •Kurt Kilian, James Ritman, Eduard Roderburg, Matthias Röder, Thomas Sefzick, and Peter Wintz — Forschungszentrum Jülich

The geometry of an elastic scattering event deals with the primarily unknown track of the beam proton and the two measurable tracks of the scattered protons. With the high precision of the new straw tracker in COSY TOF we can determine (for a small fraction) precise beam particle tracks and “see” the beam emittance.

The transverse position of a beam particle in the target plane is obtained reconstructing the interaction point *I* = (*x*,*y*,*z*_{tgt}) as intersection of the two measured tracks of the scattered protons. They make a plane, containing *I*, with a normal *n* derived from the vector product of the scattering directions. The unknown beam particle directional vector *b* lies in this plane and is orthogonal to *n*. Therefore n provides one of the two angular informations of the beam particle direction. Even the second angular information for b can be determined in the same event in some cases if we are in the regime of relativistic kinematics. From the measured sum of the scattering angles (θ_{1} + θ_{2}) and with known beam momentum we calculate θ_{1} and θ_{2}.

Such an emittance measuring system will also work behind a very thin internal cluster target in an accelerator ring. It can also give time correlations and beam polarization.