In this study, the sensitivity of future lepton colliders to weakly interacting massive particles (WIMP) dark matter is evaluated assuming WIMP pair production accompanied by a photon from initial state radiation, through which the process can be identified. A full detector simulation for the International Large Detector (ILD) concept at the International Linear Collider (ILC) is performed for a center-of-mass energy of 500 GeV. Energy scales of up to 3 TeV can be tested for different effective operators for WIMP masses almost up to half the center-of-mass energy. The sensitivity benefits from the polarized beams, which can reduce the main SM background from neutrino pair production substantially. In addition, systematic uncertainties are shown to be significantly reduced by combining data with several different polarization configurations. In comparison to a previous study, the reconstruction of the forward detectors has been improved, and the systematic uncertainties are fully treated. The results are also extrapolated to other center-of-mass energies, luminosities, and beam polarizations. This allows us to provide results for the full ILC program, i.e., from 250 GeV to 1 TeV, as well as to give approximate results for other planned lepton colliders.

WIMP dark matter at the International Linear Collider

A high energy electron positron collider is proposed to complement the large hadron collider, LHC, which has started taking data at CERN, Geneva, Switzerland. Based on superconducting acceleration technology the International Linear Collider ILC is offering a mature proposal. It will deliver high luminosity electron positron collisions at 500 GeV upgradable to 1 TeV. Experimentation at such a collider presents many unique challenges, if the huge physics potential should be harvested efficiently. In this paper after a brief review of the state of the accelerator proposal the state of the preparation of the experimental program is discussed.

/pdf/the-international-linear-collider-5cyy1r3tzq.pdf

The International Linear Collider

A compact and finely grained sandwich calorimeter is designed to instrument the very forward region of a detector at a future e+e- collider. The calorimeter will be exposed to low energy e+e - pairs originating from beamstrahlung, resulting in absorbed doses of about one MGy per year. GaAs pad sensors interleaved with tungsten absorber plates are considered as an option for this calorimeter. Several Cr-doped GaAs sensor prototypes were produced and irradiated with 8.5-10 MeV electrons up to a dose of 1.5 MGy. The sensor performance was measured as a function of the absorbed dose.

/pdf/investigation-of-the-radiation-hardness-of-gaas-sensors-in-a7vykyyx7l.pdf

Investigation of the radiation hardness of GaAs sensors in an electron beam

1 – Vinca Institute of Nuclear Sciences M. Petrovica Alasa 12-14, Belgrade – Serbia 2 – School of Physics and Astronomy, Tel Aviv University Tel Aviv – Israel 3 – LAL, University Paris-Sud, IN2P3/CNRS Orsay – France 4 – Institute of Nuclear Physics PAN, Tel Aviv University Cracow – Poland The FCAL Collaboration joins effort of more than twenty institutes studying a design of the very forward region of a detector for ILC and CLIC. Of particular importance is an accurate luminosity measurement to the level of 10

Luminosity Measurement at ILC

The multiTeV e+e− Compact Linear Collider (CLIC) is one of the options for a future high-energy collider for the post-LHC era. It would allow for searches of new physics and simultaneously offer the possibility for precision measurements of standard model processes. The physics goals and experimental conditions at CLIC set high precision requirements on the vertex detector made of pixel detectors: a high pointing resolution of 3μm, very low mass of 0.2% X0 per layer, 10 ns time stamping capability and low power dissipation of 50 mW/cm2 compatible with air-flow cooling. In this thesis, hybrid assemblies with thin active-edge planar sensors are characterised through calibrations, laboratory and test-beam measurements. Prototypes containing 50μm to 150μm thin planar silicon sensors bump-bonded to Timepix3 readout ASICs with 55μm pitch are characterised in test beams at the CERN SPS in view of their detection efficiency and single-point resolution. A digitiser for AllPix, a Geant4-based simulation framework, has been developed in order to gain a deeper understanding of the charge deposition spectrum and the charge sharing in such thin sensors. The AllPix framework is also used to simulate the beam telescope and extract its tracking resolution. It is also employed to predict the resolution that can be achieved with future assemblies with thin sensors and smaller pitch. For CLIC, a full coverage of the vertex detector is essential while keeping the material content as low as possible. Seamless tiling of sensors, without the need for overlaps, by the active-edge technology allows for extending the detection capability to the physical edge of the sensor and thereby minimising the inactive regions. Thin-sensor prototypes containing active edges with different configurations are characterised in test-beams in view of the detection performance at the sensor edge. Technology Computer-Aided Design (TCAD) finiteelement simulations are implemented to reproduce the fabrication and the operation of such devices. The simulation results are compared to data for different edge terminations.

Test-beam measurements and simulation studies of thin pixel sensors for the CLIC vertex detector

Two special calorimeters are foreseen for the instrumentation of the very forward region of the ILC detector, a luminometer designed to measure the rate of low angle Bhabha scattering events with a precision better than 10?3 and a low polar angle calorimeter, adjacent to the beam-pipe. The latter 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. The sensors of this calorimeter must be radiation hard. Both devices will improve the hermeticity of the detector in the search for new particles. Finely segmented and very compact calorimeters will match the requirements. Due to the high occupancy fast front-end electronics is needed. The design of the calorimeters developed and optimised with Monte Carlo simulations is presented. Sensors and readout electronics ASICs have been designed and prototypes are available. Results on the performance of these major components are summarised.

http://iopscience.iop.org/article/10.1088/1748-0221/5/12/P12002/pdf

Forward Instrumentation for ILC Detectors

Two special calorimeters are foreseen for the instrumentation of the very forward region of the ILC detector, a luminometer designed to measure the rate of low angle Bhabha scattering events with a precision better than 10-3 and a low polar angle calorimeter, adjacent to the beam-pipe. The latter 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. The sensors of this calorimeter must be radiation hard. Both devices will improve the hermeticity of the detector in the search for new particles. Finely segmented and very compact calorimeters will match the requirements. Due to the high occupancy fast front-end electronics is needed. The design of the calorimeters developed and optimised with Monte Carlo simulations is presented. Sensors and readout electronics ASICs have been designed and prototypes are available. Results on the performance of these major components are summarised.

Gunter Haller

Papers

Forward Instrumentation for ILC Detectors

Forward Instrumentation for ILC Detectors