In 2007 DA NE was upgraded to operate in a regime of large Piwinski angle, with a novel interacti... more In 2007 DA NE was upgraded to operate in a regime of large Piwinski angle, with a novel interaction region optics, reduced vertical beta at the interaction point, and additional sextupoles providing for Crab-Waist collisions. The specific luminosity has been boosted by more than a factor of four at low currents, and the present peak luminosity is by about a factor of 3 higher than the maximum value obtained with the original collider configuration. The DA NE commissioning as well as the first experience with large Piwinski angle and Crab-Waist collisions scheme will be reported.
A proposal of converting the DAΦNE positron ring as a high duty cycle pulse stretcher for the lin... more A proposal of converting the DAΦNE positron ring as a high duty cycle pulse stretcher for the linac beam for producing a high-intensity (up to 10 10), high-quality positron beam (with energy up to 500 MeV) for HEP experiments, mainly, but not only, motivated by light dark-particles searches, is presented. A list of the required modifications of the DAΦNE positron transfer line and main ring are presented. A dedicate lattice for the ring has been designed and tracking of the positrons injected in the ring has been performed to optimize the extraction parameters and give an estimate of the extracted beam characteristics.
DAΦNE, the Frascati lepton collider, has completed the preparatory phase in order to deliver lumi... more DAΦNE, the Frascati lepton collider, has completed the preparatory phase in order to deliver luminosity to the SIDDHARTA-2 detector. DAΦNE colliding rings rely on a new interaction region, which implements the well-established Crab-Waist collision scheme, and includes a low-beta section equipped with newly designed permanent magnet quadrupoles, and vacuum components. Diagnostics tools have been improved, especially the ones used to keep under control the beam-beam interaction. The horizontal feedback in the positron ring has been potentiated in order to achieve a higher positron current. Luminosity diagnostics have been also updated so to be compatible with the new detector design. The commissioning was initially focused on recovering the optimal dynamical vacuum conditions, outlining alignment errors, and optimizing ring optics. For this reason, a detuned optics, featured by relaxed low-b condition at the interaction point and Crab-Waist Sestupoles off, has been applied. In a secon...
SABINA (Source of Advanced Beam Imaging for Novel Applications) is a project aimed at the enhance... more SABINA (Source of Advanced Beam Imaging for Novel Applications) is a project aimed at the enhancement of the SPARC_LAB research facility. This enhancement is carried out through the following actions: first, the increase of the uptime through the consolidation of technological systems and the replacement of some critical equipment in order to limit the number and extent of faults; then, the improvement of the accelerator performances, by replacing some devices with updated ones. The effect will be greater reliability of the accelerator, which will allow it to be opened as a facility for external users, both industrial and scientific, with the goal of increasing the competitiveness of industries in a broad range of technological areas and enhancing collaborations with research institutions. The two user lines that will be implemented are a power laser target area and a THz radiation line, by using a dedicated undulator. The undulator and the THz line are also described in other contr...
The SuperB project is an international effort aiming at building in Italy a very high luminosity ... more The SuperB project is an international effort aiming at building in Italy a very high luminosity e⁺e⁻ (10³⁶ cm⁻² sec⁻¹) asymmetric collider at the B mesons cm energy. The accelerator design has been extensively studied and changed during the past year. The present design, - based on the new collision scheme, with large Piwinski angle and the use of 'crab' sextupoles, which has been successfully tested at the DAΦNE Phi-Factory at LNF Frascati, - provides larger flexibility, better dynamic aperture and in the Low Energy Ring spin manipulation sections, needed for having longitudinal polarization of the electron beam at the Interaction Point. The Interaction Region has been further optimized in terms of apertures and reduced backgrounds in the detector. The injector complex design has been also updated. A summary of the design status, including details on lattice and spin manipulation will be presented in this paper.
In March 2018 DAΦNE, the Italian electron-positron Phi-factory based on the Crab Waist collision ... more In March 2018 DAΦNE, the Italian electron-positron Phi-factory based on the Crab Waist collision concept, has successfully completed the challenging experimental run for the KLOE-2 detector. At present, installation of the SIDDHARTA-2 detector is underway in order to start data acquisition with the new experimental apparatus in the year 2019. In this paper we review the collider performances during the KLOE-2 run in terms of the achieved beam currents, the peak and integrated luminosity and encountered beam dynamics challenges. The design and development work done in view of the SIDDHARTA-2 operation is presented and discussed.
The different components of the DAΦNE accelerator complex: LINAC, Damping Ring and two colliding ... more The different components of the DAΦNE accelerator complex: LINAC, Damping Ring and two colliding rings are connected by a composite system of Transfer Lines which, thanks to adaptive configurations, are able to transport electron and positron beams at 510~MeV. Recently, thanks to the introduction of new diagnostics tools, the optics model of the DAΦNE Transfer Lines has been improved and succesfully used to make the collider operations more efficient. The measurements done by using the new tools and their impact on the optics model optimization process are presented and discussed.
A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Ph... more A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with optical transition radiation (OTR) profile monitors. Furthermore, OTR angular distribution strongly depends on beam energy. Since OTR screens are typically placed in several positions along the Linac to monitor beam envelope, one may perform a distributed energy measurement along the machine. This will be useful, for instance, during the commissioning phase of the GBS in order to verify the correct functionality of the C-Band accelerating structures, due to the fact that there are OTR screens after each accelerating module. This paper deals with the studies of different optic configurations to achieve the field of view, resolution and accuracy in order to measur...
The Extreme Light Infrastructure - Nuclear PhysicsGamma Beam System (ELI-NP GBS) will be installe... more The Extreme Light Infrastructure - Nuclear PhysicsGamma Beam System (ELI-NP GBS) will be installed and commissioned starting within the next year in Magurele,Romania. It will generate gamma beam through Comptonback-scattering of a recirculated laser and a multi-bunchelectron beam, produced by a 720 MeV LINAC. In orderto obtain bunch by bunch position measurements, four cavity beam position monitors (cBPM) near the two interactionpoints are foreseen. Extensive tests on the cBPM readout electronics, recently developed by InstrumentationTechnologies and acquired for ELI-NP GBS, were performed in laboratory at INFN-LNF and at FLASH inDESY, during the user operation. In the latter case, threecBPMs installed along the LINAC, with similar features as the ones of ELI-NP GBS, were used as measuring devices and signal sources for the read-out electronics under test.We present here the measurements collected and the related analysis, with a particular focus on the beam position measurement res...
The current activity of the SPARC LAB test-facility is focused on the realization of plasma-based... more The current activity of the SPARC LAB test-facility is focused on the realization of plasma-based acceleration experiments with the aim to provide accelerating field of the order of GV/m while maintaining the overall quality (in terms of energy spread and emittance) of the accelerated electron bunch. External injection schemes, both laser-driven and particle-driven, are considered. The current status of such an activity is presented, together with results related to the applicability of plasmas as focusing lenses in view of a complete plasma-based focusing, accelerating and extraction system.
The advanced source of Gamma-ray photons to be built in Bucharest (Romania), as part of the ELI-N... more The advanced source of Gamma-ray photons to be built in Bucharest (Romania), as part of the ELI-NP European Research Infrastructure, will generate photons by Compton back-scattering in the collision between a multi-bunch electron beam and a high intensity recirculated laser pulse. An S-Band photoinjector and the following C-band Linac at a maximum energy of 720MeV, under construction by an European consortium (EurogammaS) led by INFN, will operate at 100Hz repetition rate with trains of 32 electron bunches, separated by 16ns and a 250pC nominal charge. The different BPMs and current transformers used to measure transverse beam position and charge along the LINAC are described. Design criteria, production status and bench test results of the charge and position pickups are reported in the paper, together with the related data acquisition systems.
The design of the SuperB B -Factory [1] has been inspiration for several other proposals and is t... more The design of the SuperB B -Factory [1] has been inspiration for several other proposals and is the base of the SuperKEKB new design. SuperB was a state-of-the art accelerator for which new ideas were developed, such as the “Large Piwinski Angle and Crab Waist Sextupoles” (LPA&CW) collision scheme, super-squeezed beams, and polarized electron beam. The same design criteria were applied to a high luminosity Tau/Charm Factory designed by the INFN-LNF Laboratory in Frascati in collaboration with the Consortium Nicola Cabibbo Laboratory. The target luminosity is 10 35 cm -2 sec -1 at 4.6 GeV in the center of mass. The possibility to extend the Linac for a SASE-FEL facility was also taken into account. A Conceptual Design Report [2 ] was published in September 2013. Since the design of an intermediate energy e + e collider with high peak luminosity is still of interest for many laboratories worldwide, in this paper the design principles and the project features are summarized.
A methodology has been developed to perform electrical characterization of the stripline BPMs for... more A methodology has been developed to perform electrical characterization of the stripline BPMs for the future Gamma Beam System of ELI Nuclear Physics facility in Romania. Several prototype units are extensively benchmarked and the results are presented in this paper. The BPM sensitivity function is determined using a uniquely designed motorized test bench with a stretched wire to measure the BPM response map. Here, the BPM feedthroughs are connected to Libera Brilliance electronics and the wire is fed by continuous wave signal, while the two software-controlled motors provide horizontal and vertical motion of the BPM around the wire. The electrical oset is obtained using S-parameter measurements with a Network Analyzer (via the “Lambertson” method) and is referenced to the mechanical oset.
DAΦNE, the Frascati electron-positron collider, has completed the last, and more challenging, per... more DAΦNE, the Frascati electron-positron collider, has completed the last, and more challenging, period of operation for the KLOE-2 detector. In this context the performances of the collider, based on the Crab-Waist collision scheme, are reviewed and the limiting factors discussed.
The DAΦNE collider has been successfully commissioned after implementing major modification of th... more The DAΦNE collider has been successfully commissioned after implementing major modification of the experimental detector and a general upgradeconsolidation program involving, although to a different extent, all the accelerator complex subsystems. This paper presents the Φ-Factory setup and the achieved performances in terms of beam dynamics, luminosity, detector background and related aspects.
Optical Transition Radiation (OTR) screens are widely used for beam profile measurements. The rad... more Optical Transition Radiation (OTR) screens are widely used for beam profile measurements. The radiation is emitted when a charged particle beam crosses the boundary between two media with different optical properties. The main advantages of OTR are the instantaneous emission process allowing fast single shot measurements (i.e. bunch by bunch measurements in a multi bunch machine), and the good linearity with the beam charge (if coherent effects can be neglected). Furthermore, OTR angular distribution strongly depends on beam energy. Since OTR screens are typically placed in several positions along the Linac to monitor beam envelope, one may perform a distributed energy measurement along the machine: this will be useful, for instance, during the commissioning phase of a machine. This paper deals with the studies of an algorithm to optimize the generation and the transport of the transition radiation through an optic system using the simulation tool Zemax. The algorithm, in combinatio...
The commissioning of CNAO, the Italian Centre of Oncological Hadrontherapy, with proton beams is ... more The commissioning of CNAO, the Italian Centre of Oncological Hadrontherapy, with proton beams is completed. The real-time measurement of the synchrotron dipole field with the so-called B-train, together with its electronic systems and related software and firmware are here described. An additional magnet, powered in series with the synchrotron dipoles, is equipped with a special coil that measures the field integral variation along the beam nominal path. The voltage induced in the coil is digitized with a fast ADC and numerically integrated by an FPGA. The field integral is then distributed to the users every time that the equivalent field changes by 0.1 G. The measured B field ranges from 0 to 1.6 T with maximum ramps of 3 T/s. The B-train system will be used to provide feedback in field to the dipole power supply. It will handle the limited bandwidth of the active filter, the B-field lag in the magnets and will avoid current jumps.
DAΦNE, the Italian lepton collider, operates routinely with high intensity electron and positron ... more DAΦNE, the Italian lepton collider, operates routinely with high intensity electron and positron colliding beams. The high current multi-bunch beams are stored in two independent rings, each of them 97 m long, and are distributed into 100÷110 contiguous buckets out of the 120 available, spaced by only 2.7 ns. Since its construction, DAΦNE has been operated in different configurations which, overall, allowed to store currents up to 1.4 A and 2.45 A in the positron and in the electron beam respectively. To this day DAΦNE holds the record for the highest electron beam current ever stored in particle factories and modern synchrotron radiation sources. The DAΦNE experience, in terms of beam dynamics optimization aimed at achieving the high intensity beams, is presented with special emphasis on the e-cloud related issues which represent the dominant effect limiting the positron beam current.
DANE, the Frascati lepton collider working at the c.m. energy of the resonance, continues to b... more DANE, the Frascati lepton collider working at the c.m. energy of the resonance, continues to be a prominent infrastructure to realise experiments aimed at studying elementary particles and nuclear physics. The motivations of this long lasting interest are related to the DANE ability to increase its performances in terms of luminosity thanks to the innovative Crab-Waist collision scheme developed and implemented for the first time by the Frascati Team. In this framework, a new run for the SIDDHARTA-2 experiment has been planned in the year 2019. The detector presently installed in the interaction region, KLOE-2, will be removed and a new low- section equipped with new permanent magnets quadrupoles, will be installed. Diagnostics tools will be improved especially the ones used to keep under control the beam-beam interaction. The horizontal feedback in the positron ring will be potentiated in order to achieve a higher positron current. The design and development work done in view ...
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Papers by Angelo Stella