10 - H1 - Desy

3.2 H1 detector 41
the HERA collider has been switched off. Last few months of the HERA II running
were dedicated for the special collision with decreased proton energy to 460 GeV and
575 GeV. The decrease of the proton current is reflected in the lower slope of the integrated
luminosity plot at the end of the HERA II run.
H1 Integrated Luminosity / pb -1
Status: 1-July-2007
400
300
200
electrons
positrons
low E
HERA-2
HERA-1
100
0
0 500 1000 1500
Days of running
Figure 3.2: HERA I and HERA II integrated luminosity as a function of time.
3.2 H1 detector
The multi-purpose detector H1 was designed to measure the final state particles resulting
from the ep collisions provided by the HERA machine. Its complex set of subdetectors
build around the nominal interaction point IP allows precise identification and reconstruction
of particles emerging from the interaction. It provides almost hermetic geometrical
coverage, with the main limitation being the beam pipes.
Figure 3.3 presents the H1 detector drawn with its major components highlighted. The
IP is surrounded by the tracking system consisting of a variety of subdetectors. The innermost
system, the tracking systems is enclosed by the calorimetry dedicated to measure
energy of the final state particles. Both tracking and calorimetry systems are contained
within the homogeneous magnetic field of 1.15 T provided by superconducting magnets.
The beam energy asymmetry is reflected in the geometry of the detector. The proton
beam direction, referred to as the forward direction is significantly heavier instrumented.
The opposite, electron beam, or backward direction is dedicated predominantly to the
reconstruction of the scattered electron.