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.

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Abstract. Baryon-to-meson Transition Distribution Amplitudes (TDAs) encoding valuable new information on hadron structure appear as building blocks in the collinear factorized description for several types of hard exclusive reactions. In this paper, we address the possibility of accessing nucleon-to-pion (πN ) TDAs frompp → e + e − π 0 reaction with the futurePANDA detector at the FAIR facility. At high centerof-mass energy and high invariant mass squared of the lepton pair q 2 , the amplitude of the signal channel pp → e + e − π 0 admits a QCD factorized description in terms of πN TDAs and nucleon Distribution Amplitudes (DAs) in the forward and backward kinematic regimes. Assuming the validity of this factorized description, we perform feasibility studies for measuringpp → e + e − π 0 with thePANDA detector. Detailed simulations on signal reconstruction efficiency as well as on rejection of the most severe background channel, i.e.pp → π + π − π 0 were performed for the center-of-mass energy squared s = 5 GeV 2 and s = 10 GeV 2 , in the kinematic regions 3.0 < q 2 < 4.3 GeV 2 and 5 < q 2 < 9 GeV 2 , respectively, with a neutral pion scattered in the forward or backward cone | cos θ π 0 | > 0.5 in the proton-antiproton center-of-mass frame. Results of the simulation show that the particle identification capabilities of thePANDA detector will allow to achieve a background rejection factor of 5 · 10 7 (1 · 10 7 ) at low (high) q 2 for s = 5 GeV 2 , and of 1 · 10 8 (6 · 10 6 ) at low (high) q 2 for s = 10 GeV 2 , while keeping the signal reconstruction efficiency at around 40%. At both energies, a clean lepton signal can be reconstructed with the expected statistics corresponding to 2 fb −1 of integrated luminosity. The cross sections obtained from the simulations are used to show that a test of QCD collinear factorization can be done at the lowest order by measuring scaling laws and angular distributions. The future measurement of the signal channel cross section withPANDA will provide a new test of the perturbative QCD description of a novel class of hard exclusive reactions and will open the possibility of experimentally accessing πN TDAs.

The exclusive charmonium production process inpp annihilation with an associated π 0 mesonpp → J=ψπ 0 is studied in the framework of QCD collinear factorization. The feasibility of measuring this reaction through the J=ψ → e þ e − decay channel with the AntiProton ANnihilation at DArmstadt (PANDA) experiment is investigated. Simulations on signal reconstruction efficiency as well as the background rejection from various sources including thepp → π þ π − π 0 andpp → J=ψπ 0 π 0 reactions are performed with PANDAROOT, the simulation and analysis software framework of thePANDA experiment. It is shown that the measurement can be done atPANDA with significant constraining power under the assumption of an integrated luminosity attainable in four to five months of data taking at the maximum design luminosity.

Detector-plane prototypes of the very forward calorimetry of a future detector at an e + e − collider have been built and their performance was measured in an electron beam. The detector plane comprises silicon or GaAs pad sensors, dedicated front-end and ADC ASICs, and an FPGA for data concentration. Measurements of the signal-to-noise ratio and the response as a function of the position of the sensor are presented. A deconvolution method is successfully applied, and a comparison of the measured shower shape as a function of the absorber depth with a Monte-Carlo simulation is given.