arXiv subjects

W. Lohmann

Publications and source records attributed to W. Lohmann.

26 records · Page 2Linked to original sources

arXiv2009

Fast Beam Conditions Monitor BCM1F for the CMS Experiment

The CMS Beam Conditions and Radiation Monitoring System, BRM, will support beam tuning, protect the CMS detector from adverse beam conditions, and measure the accumulated dose close to or inside all sub-detectors. It is composed of different sub-systems measuring either the particle flux near the beam pipe with time resolution between nano- and microseconds or the integrated dose over longer time intervals. This paper presents the Fast Beam Conditions Monitor, BCM1F, which is designed for fast flux monitoring measuring both beam halo and collision products. BCM1F is located inside the CMS pixel detector volume close to the beam-pipe. It uses sCVD diamond sensors and radiation hard front-end electronics, along with an analog optical readout of the signals. The commissioning of the system and its successful operation during the first be ams of the LHC are described.

physics.ins-det↗

arXiv2009

R&D for Very Forward Calorimeters at the ILC Detector

Special calorimeters are needed to instrument the very forward region of an ILC detector. These devices will improve the hermeticity being important for new particle searches. A luminometer is foreseen to measure the rate of low angle Bhabha scattering with a precision better than 10-3. A calorimeter adjacent to the beam-pipe will be hit by a large amount of beamstrahlung remnants. The amount and shape of these depositions will allow a fast luminosity estimate and the determination of beam parameters. However, the sensors must be extremely radiation hard. Finely segmented and very compact calorimeters will match the requirements. Due to the high occupancy fast FE electronics is needed. A possible design of the calorimeters is presented and an overview on the R&D status is given

physics.ins-det↗

arXiv2007

Prospects to Measure the Higgs Boson Mass and Cross Section in ee-->ZH Using the Recoil Mass Spectrum

The process ee-->ZH allows to measure the Higgs boson in the recoil mass spectrum against the Z boson without any assumptions on the Higgs boson decay. We performed a full simulation and reconstruction of ee-->ZH using the MOKKA and MARLIN packages describing the LDC detector. The Z is reconstructed from its decays into electrons and muons. The mass of the Higgs boson is set to 120 GeV. Assuming a centre-of-mass energy of 250 GeV and an integrated luminosity of 50/fb the Higgs boson mass and the Higgs-strahlung cross section can be measured with a precision of 120 MeV and 9%, respectively.

hep-ex↗

arXiv2006

The Impact of BeamCal Performance at Different ILC Beam Parameters and Crossing Angles on \tilde{tau} searches

The ILC accelerator parameters and detector concepts are still under discussion in the world-wide community. As will be shown, the performance of the BeamCal, the calorimeter in the very forward area of the ILC detector, is very sensitive to the beam parameter and crossing angle choices. We propose here BeamCal designs for a small (0 or 2 mrad) and large (20 mrad) crossing angles and report about the veto performance study done. As illustration, the influence of several proposed beam parameter sets and crossing-angles on the signal to background ratio in the stau search is estimated for a particular realization of the super-symmetric model.

physics.acc-ph↗

arXiv2005

Beam Calorimeter Technologies

Two different technologies are considered for the Beam Calorimeters of the ILC detector. Simulation studies of the performance have been done for a diamond-tungsten sandwich calorimeter and for a homogeneous heavy element crystal calorimeter with optical fiber readout. Studies of the stability and the linearity of a polycrystalline diamond were done for the diamond-tungsten option. For the heavy crystal option the light yield reduction due to the wavelength shifting fiber readout was studied.

physics.ins-det↗

arXiv2005

Measurement of the Higgs Boson Mass with a Linear e+e- Collider

The potential of a linear e+e- collider operated at a centre-of-mass energy of 350 GeV is studied for the measurement of the Higgs boson mass. An integrated luminosity of 500 fb-1 is assumed. For Higgs boson masses of 120, 150 and 180 GeV the uncertainty on the Higgs boson mass measurement is estimated to be 40, 65 and 70 MeV, respectively. The effects of beam related systematics, namely a bias in the beam energy measurement, the beam energy spread and the luminosity spectrum due to beamstrahlung, on the precision of the Higgs boson mass measurement are investigated. In order to keep the systematic uncertainty on the Higgs boson mass well below the level of the statistical error, the beam energy measurement must be controlled with a relative precision better than 10-4.

hep-ex↗

arXiv2005

Electromagnetic and Weak Moments of the Tau-Lepton

The electromagnetic and weak dipole moments of the Tau-lepton have been measured by experiments at e+e- colliders. Data samples of e+e- --> tau+tau-, e+e- --> tau+tau- gamma and e+e- --> e+e-tau+tau- events collected at centre-of-mass energies between 10 and 200 GeV are used. No deviation from the Standard Model is found. Limits on the moments are summarised from the most recent results.

hep-ex↗

arXiv2003

Determination of the Higgs boson spin with a linear e+e- collider

The energy dependence of the production cross section of a light Higgs boson is studied at threshold and compared to the expectations of several spin assumptions. Cross section measurements at three centre-of-mass energies with an integrated luminosity of 20 fb-1 allow the confirmation of the scalar nature of the Higgs Boson.

hep-ph↗