Electrons and positrons are provided by the DAΦNE Linac Beam Test Facility (BTF). The two rings of DAΦNE cross at one interaction point, where particles are produced and experiments installed. DAΦNE delivers charged and neutral kaon beams, aimed to a broad physics programme, ranging from CPT violation, rare decays and quantum mechanics, which have been studied with the KLOE2 experiment, to precision kaonic atoms measurements with the SIDDHARTA-2 experiment, which will be installed on DAΦNE in 2018 for a data taking campaign extending in the coming years. The high antikaon beam is unique worldwide for antikaon stopped experiments, paralleled only by the J-PARC facility in Japan for antikaon in-flight reaction studies. Another experiment, AMADEUS, aiming to study the low-energy antikaon-nuclei interactions is under study. A new experiment, PADME (Positron Annihilation into Dark Matter Experiment), has been approved by INFN at the end of 2015. PADME aims to search for the “dark photon” by detecting the products of the annihilations of the positrons from the DAΦNE linac on a fixed target. The SIDDHARTA-2 experiment: SIDDHARTA-2 is a new experiment which will be installed in DAΦNE in the second half of 2018, realized taking advantage of the experience gained in the previous SIDDHARTA experiment, which has performed the most precise kaonic hydrogen measurement ever. SIDDHARTA-2 aims to perform the first measurement of the kaonic deuterium X-rays transitions to the fundamental level. This will allow to extract the antikaon-nucleon isospin dependent scattering lengths, fundamental quantities to understand the non-perturbative QCD in strangeness sector, providing a measure of the chiral symmetry breaking, having high impact in nuclear and particle physics, as well as in astrophysics (EOS of neutron stars). Other kaonic atoms transitions are also considered, in parallel with R&D developments of radiation detector technologies (connection with WPs on radiation detectors).
The following improvements of the SIDDHARTA setup lead to the SIDDHARTA-2 apparatus:
- new monolithic Silicon Drift Detector (SDD) systems, with an improved technology
- new cryogenics target system, allowing an increase of the target gas density
- new kaon monitor trigger
- a veto system
- new K+K- discriminator
These improvements will bring to a drastic increase of the signal/background ratio.
The DAΦNE Linac Beam Test Facility (BTF): The DAΦNE Linac beam-test facility (BTF), is a beam transfer-line from the DAΦNE linac, capable of providing up to 50 bunches per second of electrons/positrons with 800/550 MeV maximum energy and a variable bunch width from 1.5 to 40 ns. Each bunch consists of microbunches for a total length of 350 ps with 140 ps at top. The BTF facility can operate from single particle up to 109 particles per bunch for detector calibration purposes with extracted electron/positron beams.
The PADME experiment on BTF: The sensitivity estimate for the PADME experiment requires that the DAΦNE linac will be able to provide 50 bunches/s of 40 ns duration with 104 -105 positrons in each bunch. The present maximum positron energy of 550 MeV is assumed. In these conditions a sample of 1013-1014 positrons on target can be obtained in one year of data taking. PADME is a small scale detector composed of the following parts:
- Diamond Active target (50 μm), to measure the average beam position
- Spectrometer, to measure the charged particle momenta in the range 50-400 MeV;
- Dipole magnet, to deflect the primary positron beam
- Vacuum chamber
- Highly segmented high resolution electromagnetic calorimeter.
Services currently offered by the infrastructure: All services described for the scientific lines of LNF: SIDDARTHA-2, BTF, PADME are intended to be included in the transnational access offered within this Proposal. The interest of European scientists for transnational access to LNF within the last HadronPhysics3 (2012-2014) Project is shown by these figures: accepted projects 53, numbers of users 189, number of days spent at the infrastructure 3529.
Lead beneficiary: INFN - Italy
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