Papers by Raffaele De Monte
In BPM systems, the dependence of measured position on beam current is a well-known behaviour due... more In BPM systems, the dependence of measured position on beam current is a well-known behaviour due to many factors. Measurements were carried out at Diamond Light Source with the pilot-tone compensated RF front end developed at Elettra and they evidenced a strong link between that issue and the integral non-linearity (INL) of the ADCs. A potential way to reduce this dependence is to change the gain of the preamplifiers following the beam current variation, trying to coerce the ADC into working as close as possible to a specific level. In this paper, along with the results of the tests performed at Diamond, which confirm once again the effectiveness of the front end and of the compensation strategy, an alternative technique is proposed to mitigate the current dependence by using the pilot tone itself. The idea is to maintain constant the total amplitude at the input of the ADCs, which is composed of the signal from the beam plus the pilot tone. Our data demonstrate how, by changing th...
Bookmarks Related papers MentionsView impact
The Echo Enabled Harmonic Generation (EEHG) experiment has been implemented on the FEL2 line of t... more The Echo Enabled Harmonic Generation (EEHG) experiment has been implemented on the FEL2 line of the FERMI FEL at Elettra (Italy). The main purpose is to validate the expected performance improvements at short wavelengths before a dedicated major upgrade is deployed. This paper describes the new diagnostics and the operational experience with them during the EEHG experiment. By means of a multi position vacuum vertical manipulator, different optical components are positioned on the electron and seed laser path. Both transverse and longitudinal measurements are performed. A YAG:Ce screen (e beam) and a terbium doped UV scintillator (laser) are imaged on a dedicated CMOS camera. For the temporal alignment, an OTR screen and a scattering surface are used to steer radiation from the e-beam and laser, onto a fast photodetector. Also coherent OTR radiation, due to micro-bunching, is acquired by means of a PbSe photodetector. Finally, for the normal EEHG operation, the laser beam is injecte...
Bookmarks Related papers MentionsView impact
Elettra Sincrotrone Trieste Research Center (Elettra) is one of the Italian Institutions, togethe... more Elettra Sincrotrone Trieste Research Center (Elettra) is one of the Italian Institutions, together with Istituto Nazionale di Fisica Nucleare (INFN) and Consiglio Nazionale delle Ricerche (CNR), committed to the realization of the Italian in-kind contributions for the European Spallation Source. One part of the Elettra in-kind contributions to the proton accelerator is the construction of acquisition system for ESS Wire Scanner (WS).This paper presents an overview of the diagnostic system of the ESS Wire Scanner, including the first measurements with beam performed at CERN on LINAC4.
Bookmarks Related papers MentionsView impact
In this paper we present a novel and original four-channel front end developed for a beam positio... more In this paper we present a novel and original four-channel front end developed for a beam position monitor (BPM) system. In this work, we demonstrate for the first time the continuous calibration of the system by using a pilot tone for both beam current dependency and thermal drift compensation, completely eliminating the need for thermoregulation. By using this approach, we were also able to investigate several odd and well-known behaviours of BPM systems; the influence of important issues, like the non-linearity of ADCs and the gain compression of amplifiers, which do affect the reliability of the measurement, have been fully understood. To achieve these results, we developed a new radio-frequency front end that combines the four pick-up signals originated by the beam with a stable and programmable tone, generated within the readout system. The signals from a button BPM of Elettra storage ring have been acquired with a 16-bit, 160 MS/s digitizer controlled by a CPU that evaluates ...
Bookmarks Related papers MentionsView impact
FERMI is the seeded FEL user facility in Trieste, Italy, producing photons from the VUV to the so... more FERMI is the seeded FEL user facility in Trieste, Italy, producing photons from the VUV to the soft X-rays with a high degree of coherence and spectral stability. Both FEL lines, FEL-1 and FEL-2, are now available for users, down to the shortest wavelength of 4 nm. We will report on the completion of the commissioning of the high energy FEL line, FEL-2, and on the operational experience for users, in particular those requiring specific FEL configurations, like two-colour experiments. We will also give a perspective on the improvements and upgrades which have been triggered by our experience and are aiming to maintain as well as to constantly improve the performance of the facility for our user community.
Bookmarks Related papers MentionsView impact
this …, 2006
The Elettra new full energy injector will be based on a 100 MeV linac pre-injector, a 2.5 GeV boo... more The Elettra new full energy injector will be based on a 100 MeV linac pre-injector, a 2.5 GeV booster synchrotron and two new beam transfer lines. It will replace the existing 1.2 GeV linac injector and transfer line. Full funding was finally available in 2005, which ...
Bookmarks Related papers MentionsView impact
Long-term stability is one of the most important properties of the BPM readout system. Recent dev... more Long-term stability is one of the most important properties of the BPM readout system. Recent developments on pilot tone capable front end have been tested with an established BPM readout electronics. The goal was to demonstrate the effectiveness of the pilot tone compensation to varying external conditions. Simulated cable attenuation change and temperature variation of the readout electronics were confirmed to have no major effect to position data readout. The output signals from Elettra front end (carrier frequency and pilot tone frequency) were processed by a Libera Spark with the integrated standard front end which contains several filtering, attenuation and amplification stages. Tests were repeated with a modified instrument (optimized for pilot tone) to compare the long-term stability results. Findings show the pilot tone front end enables great features like selfdiagnostics and cable-fault compensation as well as small improvement in the long-term stability. Measurement reso...
Bookmarks Related papers MentionsView impact
In this contribution, we describe the advantages of the pilot tone compensation technique that we... more In this contribution, we describe the advantages of the pilot tone compensation technique that we implemented in a new BPM prototype for Elettra 2.0. Injecting a fixed reference tone upstream of cables allows for a continuous calibration of the system, compensating the different behaviour of every channel due to thermal drifts, variations of cable properties, mismatches and tolerances of components. The system ran successfully as a drop-in substitute for a Libera Electron not only during various machine shifts, but also during a user dedicated beamtime shift for more than 10 hours, behaving in a transparent way for all the control systems and users. The equivalent RMS noise (at 10 kHz data rate) for the pilot tone position was less than 200 nm on a 19 mm vacuum chamber radius, with a long-term stability better than 1 μm in a 12-hour window. Two main steps led to this important result: firstly, the development of a novel RF front end that adds the pilot tone to the signals originated...
Bookmarks Related papers MentionsView impact
FERMI, the seeded Free Electron Laser (FEL) located at the Elettra laboratory in Trieste, Italy, ... more FERMI, the seeded Free Electron Laser (FEL) located at the Elettra laboratory in Trieste, Italy, consists of two FEL lines. The FEL-1 facility, covering the wavelength range between 20 and 100 nm, was officially opened to external users. The shorter wavelength range, between 20 and 4 nm, is covered by the FEL-2 line, a double stage cascade operating in the “fresh bunch injection” mode, which is still under commissioning. We will report on the different FEL-1 operation modes that can be offered for users and assess the performance of the facility. The progress in the commissioning of FEL-2 will then be addressed, in particular reporting the performance attained at the lower wavelength limit; this aspect is of great interest for the user’s community of the FERMI seeded FEL since it allows to carry out experiments below the carbon K-edge.
Bookmarks Related papers MentionsView impact
FERMI is the seeded Free Electron Laser (FEL) user facility at the Elettra laboratory in Trieste,... more FERMI is the seeded Free Electron Laser (FEL) user facility at the Elettra laboratory in Trieste, operating in the ultraviolet to soft X-rays spectral range; the radiation produced by the seeded FEL is characterized by a number of desirable properties, such as wavelength stability, low temporal jitter and longitudinal coherence. In this paper, after an overview of the FEL performances, we will present the development plans under consideration for the next 3 to 5 years. These include an upgrade of the linac and of the existing FEL lines, the possibility to perform multipulse experiments in different configurations and an Echo Enabled Harmonic Generation (EEHG) experiment on FEL-2, the FEL line extending to 4 nm (310 eV). INTRODUCTION A first upgrade program of FERMI was completed beginning of 2016, with the installation of two new linac structures, an additional undulator segment for the radiator of the first stage of FEL-2 and a second regenerative amplifier for the seed laser syste...
Bookmarks Related papers MentionsView impact
FERMI is the seeded Free Electron Laser (FEL) user facility at the Elettra laboratory in Trieste,... more FERMI is the seeded Free Electron Laser (FEL) user facility at the Elettra laboratory in Trieste, operating in the VUV to EUV and soft X-rays spectral range; the radiation produced by the seeded FEL is characterized by wavelength stability, low temporal jitter and longitudinal coherence in the range 100-4 nm. During 2018 a dedicated experiment has shown the potential of the Echo Enabled Harmonic Generation (EEHG) scheme [1] to cover most of this spectral range with a single stage cascade [2]. Such a scheme, combined to an increment of the beam energy and of the accelerator performances, could extend the FERMI operating range toward the oxygen k-edge. With this perspective, we present the development plans under consideration for the next 3 to 5 years. These include an upgrade of the linac and of the existing FEL lines, consisting in the conversion of FEL-1 first, and FEL-2 successively, into EEHG seeded FELs.
Bookmarks Related papers MentionsView impact
A new timing system has been developed to operate the new injector for the Elettra storage ring. ... more A new timing system has been developed to operate the new injector for the Elettra storage ring. It implements a versatile injection system to support standard and exotic fillings as well as the top-up mode of operation. Based on an in-house developed programmable counter VME board, the system provides all the needed triggers by the pre-injector LINAC, the booster injection, the booster ramping system, the booster extraction, and the SR injection. An overview of the system architecture and functionality is described and the performance of the board is reported. All the trigger signals are distributed to the timing clients by means of optical links. SYSTEM SPECIFICATIONS The timing system of the new Elettra injector has to provide trigger signal to drive: • The thermo ionic gun • The power amplifier of the 100MeV linac • The booster injection fast magnets KIB & SIB • The booster magnet power converters • The booster extraction fast magnets KEB & SEB • The storage ring injection fast ...
Bookmarks Related papers MentionsView impact
FERMI has reached its nominal performance on both FEL lines, FEL-1 (12 eV to 62 eV) and FEL-2 (62... more FERMI has reached its nominal performance on both FEL lines, FEL-1 (12 eV to 62 eV) and FEL-2 (62 eV to 310 eV). After a brief overview of the activities with users, we will describe plans for LINAC, FEL and beamline upgrades for 2016-2018 and beyond. This includes EEHG schemes for FEL-2. INTRODUCTION FERMI is the seeded Free Electron Laser (FEL), operating in the VUV to soft X-rays range, located at the Elettra laboratory in Trieste, Italy [1]. FERMI is the only FEL user facility designed to operate in the seeded HGHG mode [2] and has successfully demonstrated operation from 100 nm down to 4 nm [3, 4]. The VUV to EUV FEL line, FEL-1, started operation with external users, i.e. selected by the FERMI Review Panel, in December 2012. Since then a period of actual commissioning of the source with users has been conducted, in a strong interaction between machine and laser team and the users. This resulted in proposing and implementing innovative solutions and schemes for pumpprobe experi...
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
AIP Conference Proceedings, 2000
ABSTRACT A prototype Low Gap BPM system has been installed at ELETTRA and it is now undergoing th... more ABSTRACT A prototype Low Gap BPM system has been installed at ELETTRA and it is now undergoing the first tests. The main purpose of this system is to provide ultra-stable position signals, at the micrometer level, to the Orbit Feedback processors. The system consists of a new Low Gap monitor and a new digital BPM electronics. The monitor was designed at ELETTRA and fits to the 14 mm low gap ID vacuum chamber. Full advantage has been taken from the reduced gap button distance. To reach maximum stability of the BPM itself, a new support system has been designed where, by means of two bellows, the BPM movements are de-coupled from the vacuum chamber slow drifts. Furthermore an external system monitors the BPM position with respect to a reference column made of carbonium. The Low Gap BPM system adopts the digital BPM electronics that was conceived at the Paul Scherrer Institut for the Swiss Light Source (SLS). One of its features is the programmable bandwidth that offers sub-micron position data when set to low bandwidth (<1 kHz). The project evolved into a successful collaborative development between ELETTRA, APL, SLS and the company Instrumentation Technologies. In this paper the first results obtained on the ELETTRA Storage Ring are presented and future system integration is outlined. © 2000 American Institute of Physics.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Some of the TTF cryomodules have been equipped with wire position monitors (WPM) in order to moni... more Some of the TTF cryomodules have been equipped with wire position monitors (WPM) in order to monitor on line the displacements of the cold mass to verify alignment stability and reproducibility. Based on the operation experience of the first prototypical cryomodules, equipped with up to 36 WPMs distributed in two strings, on the last generation cryomodules a single string of 7 sensors has been installed. Here we review and analyse the data collected so far to prove that the proposed cryomodule design is consistent with the TESLA alignment requirements.
Bookmarks Related papers MentionsView impact
2011 International Conference on Electromagnetics in Advanced Applications, 2011
... References [1] CJ Bocchetta et al., FERMI@Elettra Con-ceptual Design Report, Sincrotrone Tr... more ... References [1] CJ Bocchetta et al., FERMI@Elettra Con-ceptual Design Report, Sincrotrone Trieste, Tech. Rep. ... [7] A. Borga, The Diagnostics' Back-End Plat-form Based on the In House Developed A|D|A And A|D|O Boards, BIW2010, Santa Fe, New Mexico, US, May 2010. ...
Bookmarks Related papers MentionsView impact
Uploads
Papers by Raffaele De Monte