The goal of the AEḡIS experiment at the Antiproton Decelerator (AD) at CERN, is to measure directly the Earth's gravitational acceleration on antimatter by measuring the free fall of a pulsed, cold antihydrogen beam. The final position of the falling antihydrogen will be detected by a position sensitive detector. This detector will consist of an active silicon part, where the annihilations take place, followed by an emulsion part. Together, they allow to achieve 1% precision on the measurement ofḡ with about 600 reconstructed and time tagged annihilations. We present here the prospects for the development of the AEḡIS silicon position sentive detector and the results from the first beam tests on a monolithic silicon pixel sensor, along with a comparison to Monte Carlo simulations.-2 -2 antimatter by measuring the Earth's gravitational acceleration g for antihydrogen. Several attempts 3 have been made in the past to measure the gravitational constant for antimatter, both for charged 4 [2, 3] and neutral antiparticles [4, 5, 6]. However, none of these experiments brought to conclusive 5 results. Recently, a study from the ALPHA collaboration [7] sets limits to the ratio of gravitational 6 mass to the inertial mass of antimatter but is yet far from testing the equivalence principle. Another 7 experiment, GBAR, [8] has been proposed but not yet built. 8 Cold antihydrogen (100 mK) in Rydberg states will be produced through the charge exchange 9 reaction between Rydberg positronium and cold antiprotons stored in a Penning trap [9]. Applying 10 an appropriate electric field will accelerate the formed antihydrogen in a horizontal beam, with a 11 typical axial velocity distribution spanning a few 100 m/s [10]. 12Some of the trajectories will be selected through a moiré deflectometer [11], which will consist 13 of two vertical gratings producing a fringe pattern on a downstream annihilation plane (see fig. 2). 14 This plane will be the first layer of the position sensitive detector where the antihydrogen will 15 impinge with energies of the order of meV and annihilate. The vertical deflection of the pattern 16 is proportional to the gravitational constant to be measured. Over a flight path of ∼ 1 m, the 17 deflection is expected in the order of ∼ 20 µm for a 1 g vertical acceleration [1]. A vertical 18 resolution better than 10 µm is required to meet the goal of 1% precision on theḡ measurement 19 with 600 reconstructed and time tagged annihilations [12]. 20According to the current design, the position sensitive detector will be a hybrid detector con-21 sisting of an active silicon part, where the annihilation takes place, followed by an emulsion part 22 65 the fragmentation of excited hadronic systems into individual hadrons, whereas the FTFP model 66 [23] relies on a string model to describe the interactions between quarks. 67The CHIPS and FTFP models differ in the production rate and in the composition of the 68 annihilation products. CHIPS produces heavy nuclear fragments in only 20 % of the events while 69 FTFP...

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The AEgIS Experiment is an international collaboration based at CERN whose aim is to perform the first direct measurement of the gravitational acceleration g of antihydrogen in the gravitational field of the Earth. Cold antihydrogen will be produced with a pulsed charge exchange reaction in a cylindrical Penning trap where antiprotons will be cooled to 100 mK. The cold antihydrogen will be produced in an excited Rydberg state and subsequently formed into a beam. The deflection of the antihydrogen beam will be measured by using Moiré deflectometer gratings. After being approved in late 2008, AEgIS started taking data in a commissioning phase early 2012. This report presents an overview of the AEgIS experiment, describes its current status and shows the first measurements on antiproton catching and cooling in the 5 T Penning catching\ud trap.We will also present details on the techniques needed for the 100mK antihydrogen production, such as pulsed positronium production and its excitation with lasers

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