M. Biagini, INFN-LNF For the Tau/charm Study Group XCIX Congresso SIF, Trieste 25 /09/13
Overview A t/charm Factory, an e+e- collider with very high luminosity at the 2-4.5 GeV center of mass energy, to be built on the Rome University at Tor Vergata campus, was studied by the Consorzio N. Cabibbo Laboratory and the INFN Frascati Laboratories This project is the natural evolution of the flagship Italian project SuperB Factory, funded by the Italian Government in 2010 with a budget that turned out to be insufficient to cover the total costs of the project, and then cancelled in Dec. 2012 The study of rare events at the t/charm energy was already planned as a Phase-II of SuperB. This design keeps all the unique features of SuperB, including the polarization of the electron beam, with the possibility to take data in a larger energy range, with reduced accelerator dimensions and construction and operation costs
Accelerator study group LNF team CabibboLab team M. Biagini M. Boscolo A. Chiarucci A. Clozza A. Drago S. Guiducci C. Ligi G. Mazzitelli R. Ricci C. Sanelli M. Serio S. Tomassini ESRF & Pisa team P. Raimondi S. Liuzzo E. Paoloni LNS team G. Schillaci M. Sedita S. Bini F. Cioeta D. Cittadino M. D Agostino M. Del Franco A. Delle Piane E. Di Pasquale G. Frascadore S. Gazzana R. Gargana S. Incremona A. Michelotti L. Sabbatini
t/charm Factory main features Energy tunable in the range E cm = 1-4.8 GeV 10 35 cm -2 s -1 peak luminosity at the t/charm threshold and upper Symmetric beam energies Longitudinal polarization in the electron beam (60-70%) Possibility of e - e - collisions (to be studied) Beam parameters for reasonable lifetimes and beam currents Low power consumption lower running costs Injection system scaled from the SuperB one Possible applications: SASE-FEL @2.4 6 GeV Beam Test Facility line
Beam parameters Beam parameters to reach a baseline luminosity of 10 35 cm -2 s -1 @ 2 GeV/beam have been chosen An upgrade to 2x10 35 cm -2 s -1 can be possible by increasing the beam current Design features are the same as for the SuperB design: Large Piwinski angle & crab waist sextupoles collision scheme Low H-emittance lattice Small H-V coupling ultra low V-emittance Small IP b functions and beam sizes Beam-beam tune shifts < 0.1 Same RF frequency as PEP-II (re-use of cavities) Low beam power
Table of parameters @ 2 GeV/beam Baseline design L=10 35, with possibility to increase currents for 2x10 35 cm -2 s -1 Intra Beam Scattering and hourglass factors included Beam power about 15 times less than the SuperB baseline one (4 MW (HER) and 2MW (LER) of RF power)
Luminosity vs Energy At low energy (last column) insertion of 8 wigglers is foreseen to keep same damping times Polarization will be maximum around 4 GeV c.m
Tau-Charm Layout @ Tor Vergata
t-charm complex view IP Storage Rings (preliminary) Damping Ring TLs LINAC
Main Rings lattice: Arc X Sexts mux=3pi muy=pi X Octupoles Y Sexts mux=3pi muy=pi The sextupoles arrangement allows for a very good correction of non-linearities and provides a very large dynamic aperture without the Final Focus
Main Rings lattice: Final Focus Y Sexts mux=muy=pi Crab Sext X Sexts mux=muy=pi Y Off Phase Sexts X Off Phase Sexts The Final Focus sextupoles need to compensate for the huge chromaticity coming from the final doublets. Their effect on the dynamic aperture is important but has been minimized as much as possible
Final Chosen tolerated Values S.M.Liuzzo, ESRF, Università Tor Vergata 15
Lifetimes and backgrounds Backgrounds and lifetime are two issues strictly connected one to the other, even if they have different implications for the accelerator design and operation, being determined by the same physical process that may induce particle losses Backgrounds can be cured with detectors shielding, masking and collimator systems, while a short lifetime can be handled with continuous top-up injections A Monte Carlo simulation is used to determine the beam lifetimes and the beam-stay-clear needed for acceptable beam loss rates
Beam lifetimes estimate
Focus collimation system Final (similarly Focus to SuperB) collimation system e located where bx and Dx are large SECONDARY PRIMARY H-collimators COL1 COL2 COL3 COL4 SFX0 SFX4 SDY0 SDY4 High Luminosity, May 29th 2013 V-collimators 20 20
Main Rings magnets Dipol e Gradient dipole Sextupole Quadrupole
!CHAOS Control System!CHAOS (Control System based on Highly Abstracted Operating Structure) is the proposed software infrastructure to realize the Control System Chaos can be view as a distributed computer UI,EU are the CPUs running user applications KVDB is the HardDisk DOC is the RAM BSON is the BUS CUs are the drivers attached to devices
Damping Ring mechanical layout Main Rings Damping Ring
Main Rings side by side The present maximum separation between main rings is about 3.5m 3.5m
Feedbacks
t-charm alignment case study Primary Network Secondary Network Only the outer reference points of the secondary network are visible.
Tau-Charm Injection System The preliminary layout of the injection system is based on the design of the SuperB injection system The same design for the linac and damping ring lattice is used The main difference with respect to the SuperB design is the fact that only positrons are stored in the Damping Ring (DR) As for the SuperB case, the linac can be used to accelerate electron pulses for an FEL synchrotron light source
Tau-Charm Injection System Positron Source DR Bunch Compressor FEL photoinjecto r 0.6 GeV 1.0 GeV 1.3 GeV Linac L1 e - Bypass Linac L2 e + Total electron linac energy 2.9 GeV Total positron linac energy 2.3 GeV e - Linac L3 FEL Line e - e + To MRs Linac L1 Linac L2 Linac L3 N. of klystrons 3 6 7 N. of cavities 9 18 21 Max. Energy (GeV) 0.62 1.24 1.45 The number of klystrons and cavities allows to reach the maximum positron energy of 2.3 GeV also with one klystron off
Positron Damping Ring The preliminary magnetic layout of the damping ring is completed The mechanical design of magnets and supports is in progress The mechanical layout is ready for next step: vacuum, diagnostic, radio frequency, survey and alignment
DR magnets design Dipoles Long And short Quadrupoles Sextupole s
magnets are needed to separate the FEL bunches from the Tau/Charm bunches in the region of the positron converter and other two can be used in the region of Damping Ring injection and Tau/charm extraction, between linac L2 and L3. In this a regions SASE-FEL two magnetic bunch compressor systems can be installed, suitably designed to increase the peak current. A layout of the Tau/Charm complex with the FEL facility is shown in Figure 7.1. 1. Linac tunnel 2. Modulator and klystron building 3. Damping Ring 4. Main Rings 5. Collider hall 6. Assembly hall 7. Vacuum Lab 8. Cryo Lab 9. Magnetic measurement 10. HVAC building 11. Electric station 12. Electric substation 13. Linac banda C tunnel 14. Undulators unnel 15. Experimental hall Figure 7.1 - Tau/Charm complex with the SASE-FEL option. Possibility to drive a SASE X-ray FEL using the 2.4 GeV Tau/Charm Linac To estimate the photons wavelength we consider an electron beam that traverses an To achieve an energy of 6 GeV (1.5 and 3 Angstrom photon wavelength) undulator, emitting electromagnetic radiation at the resonant wavelength: additional Linac sections can be installed at the end of the last Linac, using (7.1) the C-band (f = 5712 MHz) technology, which is being developed at LNF in the framework of the EU-TIARA project, and will be soon mounted at SPARC-LAB Assuming an accelerating gradient of 40 MV/m, additional 80 m of Linac sections (about 40) should be added (total Linac length 300 m)
Accelerator Report Distributed mid-july, INFN-LNF publication September
Accelerator Report ToC 1. Introduction 2. Collider Main Rings - Luminosity and Beam parameters - Main Rings lattice - Interaction Region design - Dynamic Aperture and tolerance to errors - Backgrounds and lifetimes - Intra Beam Scattering - E-cloud instability 3. Injection Complex - General layout - Positron Source - Damping Ring - Linac specifications - Transfer Lines - Injection into the Main Rings 4. Accelerator Systems Diagnostics Feedbacks Controls Vacuum Sysstem Radio Frequency Magnets (DR, MR) Mechanical engineering Survey and alignment Power electronics 5. Conventional Facilities - Site - Mechanical layout - Infrastructures and civil engineering - Fluids - Cryogenics - Electrical engineering - Health Safety and Environment 6. Costs and schedule 7. Tau/charm as a SASE-FEL facility 8. Tau/charm as a beam Test Facility
Conclusions A new infrastructure for a low energy Flavour Factory, with possible applications in other fields such as FEL and BTF has been designed A Report on the accelerator design (150 pp.) has been published and can be the base for a fast TDR phase The N. Cabibbo Laboratory is in place to construct and run such a facility The estimated cost of the facility would be entirely covered by the promised SuperB funding However a decision on the future of the Flagship projects has not been taken yet, and the PNR (Piano Nazionale Ricerca) for the next 3 years is still in progress INFN will have to take a final decision before the end of this year