PADME: stato preparazione dell’esperimento e piani M. Raggia,b, P. Valenteb a Sapienza Università di Roma, b INFN Roma

Invisible final state A’→cc The physics case(s) PADME è presente nella review più importante del settore (Dark Sectors 2016: Community report) per il suo potenziale nei decadimenti invisibili del dark photon, ma è anche citato tra gli esperimenti che possono migliorare la comprensione di altre due classi di modelli: axion-like particles e protophobic boson Dark Photon arXiv:1608.08632v1 ALPs and g-2 arXiv 1607.01022v2 Fifth force arXiv:1608.03591v1 Invisible final state A’→cc (g+missing mass) ALPs final state a→gg (ggg or egg) Final state X→e+e- CSN 1 - March 2017

Status of dark photon searches “Visible” final states (A’l+l-) A’-strahlung: e- dumps thin target: bump hunt, displaced vertices e+e-  A’g p0,h  A’g _ “Invisible” final states (A’cc ) A’-strahlung: Missing energy e+e-  A’g , A’  cc Mono-photon events in e+e- colliders Fixed-target annihilations CSN 1 - March 2017

Limits on ALPs coupling to photons Axion-like particles Limits on ALPs coupling to photons Primakoff Bremsstrahlung Annihilation g-2 arXiv:1607.01022v2 PADME can search for long-living ALPs looking for 1 g + M2miss final states In the visible final state agg all production mechanisms can be exploited, extending the mass range in the region of ≈100MeV The observables at PADME will be egg or ggg; practically background-free above 24 MeV/c2 arXiv:1512.03069 ALP decay to photons gg invariant mass ALP contribution to (g-2) +

Protophobic vector boson 6.8s excess, interpred as a new (vector is favored) boson Largely not compatible with present limits: too high coupling unless… A. Krasznahorkay et al., “Observation of Anomalous Internal Pair Creation in 8Be: A Possible Indication of a Light, Neutral Boson”, Phys. Rev. Lett. 116, 042501 (2016) J. Feng et al., “Protophobic Fifth Force Interpretation of the Observed Anomaly in 8Be Nuclear Transitions”, Phys. Rev. Lett. 117, 071803 (2016) 8Be NA48/2 With different couplings to fermions (not the usual kinetic mixing ), it is still possible to escape the limits for a 17 MeV protophobic boson CSN 1 - March 2017

Sensitivity Candidate signal selection (simple and robust cuts) Just one cluster in the calorimeter 30 mrad < θCl < 65 mrad Emin(MA’) < ECl < Emax(MA’) No track in the positron veto within ±2 ns No cluster in small angle with E>50 MeV within ±2ns Missing mass in the region: MA’ ± σMmiss(MA’) MC simulation extrapolated to 1x1013 e+ on target Using N(A’g)=s(NBkg) With very simple cuts, far from 0-background sensitivity: improvement is possible Cross-section enhancement due to A’ mass CSN 1 - March 2017

Cross section at PADME GEANT4 low energy EM libraries CSN 1 - March 2017

Final setup e+ g A’ Dipole magnet Calorimeter Small Angle PbF2 High Energy Positron veto 1 cm scintillators SiPM readout Dipole magnet 23 cm gap (MBP-Short, transfer line SPS) Si pixel veto e+ Calorimeter BGO crystals 21×21x230 mm3 Positron veto 1 cm scintillators SiPM readout Diamond target 50-100 mm g Vacuum vessel Small Angle PbF2 Electron veto 1 cm scintillators SiPM readout A’ CSN 1 - March 2017

Beam region and vacuum chamber MIMOSA beam tracker Diamond target Baseline layout available for both vacuum chamber and target region Details to be fixed New board to operate the MIMOSA chips in vacuum being designed CSN 1 - March 2017

Active target electronics Diamond readout: CSA Amadeus chip chosen Timing performance degraded but good signal to noise Adequate performance for charge measurement Final carrier board designed, in production end of March Residual gas analysis Dominated by water Heating in vacuum not a issue Thermo-camera + quartz window + ZnSe lens setup Residual gas analysis Heating in vacuum New carrier board CSN 1 - March 2017

Diamond target Vacuum vessel & mechanics test Mechanics and motorized system ready Vacuum tests: 9 10-8 (after few h) without, 7 10-7 (after 24h) with FE board Both graphite and metallic strips targets ready Both 50 and 100 μm samples available CSN 1 - March 2017

Calorimeter/1 Test with electrons at BTF with 5×5 prototype: 20×20×220 mm3 BGO crystals + HZC XP1912 PMT’s Energy resolution 2.3% at 1 GeV Contribution of BTF energy spread almost negligible Submitted to Nucl. Instrum. Meth. A, arXiv:1611.05649 CAEN V1742 at 1 GS/s digitizers Results are very reassuring, however we feel that one more final beam-test is needed: HZC XP1911 selected (better dark current wrt XP1912) Improvement of the standard voltage divider (type B) requested to HZC PMT’s were glued, but only in the central 3×3 part of the matrix (and with two different types of glue: UV cured and EJ optical glue) Crystals were wrapped, while we plan to paint them No energy point below 250 MeV (we went down to <100 MeV with the previous test with 3×3 prototype and no glue) CSN 1 - March 2017

Dose estimates In the central crystals ~10-4 Gy for 1013 e+ on target Synchrotron radiation on the left side also visible ~1 Gy for 1013 e+ on target in the very central crystal of the small angle detector On BGO, we saw a decrease in light yield only at ~Gy, getting severe (1 order of magnitude) at 0.1-1 kGy, but recovering with time and high-temperature annealing No effect on the PMT’s CSN 1 - March 2017

Calorimeter/2 650 PMT’s: tender assigned: HZC XP1911 HV supply: tender assigned: CAEN A7030 + SY4527 19 mm PMT Waveform digitizers: tender assigned: CAEN V1742 1 – 5 GS/s 896 channels (Calorimeter + Veto detectors + Target) CSN 1 - March 2017

Calorimeter/3 Crystals preparation completed 720 crystals, of different shapes and sizes, extracted from L3 e.m. calorimeter end-cap High-temperature annealing Travelling from CERN on March 23th Machining, gluing and painting: tender assigned: Gestione SILO Transparency already good: only a slight effect of annealing CSN 1 - March 2017

Calorimeter/4 Holder done with clamp Holder done with vacuum suckers CSN 1 - March 2017

Calorimeter/5 Mechanical structure and assembly procedure: advanced design Mock-up being prepared CSN 1 - March 2017

Optimized positron veto geometry Increased scintillator dimension from 16 cm to 18.4 cm New clear area 17.4 vs 16 cm Better veto efficiency and less passive material CSN 1 - March 2017

Veto detectors 10×10x184 mm3 scintillator All scintillator bars delivered Design of the mechanics ready Prototype of the mechanical assembly ready Prototype electronics prototype ready Test-beam in April to measure efficiency and time resolution Read-out by same digitizing system as calorimeter (ready) CSN 1 - March 2017

In-beam veto Prima dei tagli Fondo residuo: soft g e+ molto vicino alla traiettoria nominale Idea: un rivelatore a pixel, con buona risoluzione temporale, in grado di fare imaging del fascio con la coda radiativa Per esempio: array di FitPIX (14×14 mm2), ToA e ToT No beam divergence With beam divergence/single beam pulse Nell’originaria suddivisione dei costi, nel 2018 150k per questo tipo di rivelatore CSN 1 - March 2017

Small angle calorimeter Cherenkov detector: fast, high rate. First design: SF57 (ex-OPAL, already used for NA62 large-angle photon veto) 7×7 square matrix, 20×20×200 mm3 16 mm fast PMT (Hamamatsu R9880-U110, 8.5 mm active diameter) After-pulses due to light reflected from crystal front face Removed with black tape on the front face -20% of collected light: 0,083 p.e./incident MeV 2 ns double pulse separation, 700 ps width Two issues: Small PMT active area (57/400 mm2 = 14%) Transparency of SF57 cut at 400 nm New design: PbF2, 5×5 square matrix, 30×30×150 mm3 Hamamatsu R13748 1” PMT (380/900 mm2 = 42%), but lower Q.E. Smaller X0 and RMolière CSN 1 - March 2017

Small angle calorimeter Loan of two PbF2 crystals from g-2 experiment (Fermilab) Grazie a G. Venanzoni e D. Herzog Waiting for a few R13478 pieces from Hamamatsu R9880 R13478 untapered R13478 tapered CSN 1 - March 2017

(tra parentesi: impulso lungo) Electron gun Nov. 8th: Gun at 150 ns, flat pulse, >510 MeV, 1% spread End of LINAC Ancora è necessario del lavoro di ottimizzazione del LINAC allo scopo di ottenere il miglior possibile spread in energia e – di conseguenza – un impulso più piatto su un intervallo temporale più lungo possibile WCM at BTF target SF57 crystal signal SF57 crystal signals time distribution CSN 1 - March 2017

Progress on Monte Carlo CSN 1 - March 2017

Online computing CSN 1 - March 2017

Offline computing Accordo per ospitare il Tier1 di PADME a LNF Connessione ideale con area sperimentale e librerie a nastro (CNAF e LNF) Ottimo supporto e disponibilità informazioni Grazie Elisabetta Vilucchi! Tier1 PADME << Tier2 ATLAS Finanziati per il 2017: 1000HepSpec (10K€) → inseriti nelle richieste LNF per il prossimo acquisto di CPU (gestito dal CNAF) Tempi lunghetti (qualche mese) Nel frattempo disponibilità ad utilizzo delle risorse attuali in modalità opportunistica Necessario spazio disco locale come buffer di lavoro Ricostruzione, analisi Per il 2018 richieste di CPU e disco per completare il Tier1 CSN 1 - March 2017

Parliamo di €€€€€ CSN 1 - March 2017

Summary of tenders 2016 2016: 4 tenders completed 630 Crystal preparation: Cutting, polishing, painting and PMT gluing of the crystals Gestione SILO 65 kEuro No savings Calorimeter HV system CAEN SY4527 Main frame with ~630 single channels, A7030 48 ch. boards 84 kEuro Saved 1 kEuro 630 PMT, 19mm with divider HZC Photonics 106+VAT+customs=138K€ Saved 22 k€ Readout: 28 digitizer boards, 32 channels CAEN V1742 226 K€+IVA, saved 29 K€ We ask to recover the savings in the 2017 budget Total savings 51K€ CSN 1 - March 2017

Assegnazioni 2017 50 mecc. ECAL 35 Vac. 10 FE Veti CSN 1 - March 2017

Missioni 2017 Sofferenza a Roma a causa di: Missioni dei tecnici al CERN per recupero cristalli BGO Raggi non fa più parte del programma Ministero Esteri – USA Inoltre Raggi (co-PI e RN) passato a Roma CSN 1 - March 2017

Costi small angle detector Assegnazione SAC 2017 = 41 kEuro costo totale del rivelatore Costi previsti nuovo disegno: 25× (650+IVA) = 20 kEuro , fast PMT’s (Offerta Hamamatsu H13478-UV) 25× (2000+IVA) = 61 kEuro, PbF2 (Offerta SICCAS) Per realizzare il rivelatore small angle mancherebbero 40 kEuro, ma abbiamo risparmiato 52 kEuro dai ribassi delle gare 2016, che appunto chiediamo di recuperare CSN 1 - March 2017

1 nuova dott. in corso d’anno Anagrafica 2017 Ricercatori e Tecnologi INFN Lecce G. Chiodini 30% (RL) S. Spagnolo 20% Pietro Creti (I tec) 20% Viviana Scherini ass INFN 30% INFN Lecce & Università Salento A. Caricato (ric) 30% G. Maruccio (Professore) 20% M. Martino (Professore) 30% A. Monteduro (AdR) 20% 2.0 FTE INFN LNF (Divisione Ricerca) P. Albicocco 30% R. Bedogni 20% F. Bossi 30% B. Buonomo (20%) R. De Sangro 20% G. Finocchiaro 20% L. Foggetta (20%) G. Georgiev (Università Sofia) 50% A. Ghigo (10%) P. Gianotti 30% (RL) V. Kozhuharov (Università Sofia) 50% M. Palutan 20% G. Piperno (A.d.R.) 100% I. Sarra (A.d.r) 20% B. Sciascia 20% T. Spadaro 20% E. Spiriti 10% C. Taruggi 100% (Dott. Tor Vergata) 4.9+1 FTE INFN Roma P. Valente 50% (RL) F. Ferrarotto 50% E. Leonardi 50% (Tecnologo) S. Fiore (ENEA) 20% F. Ameli 20% (Tecnologo) INFN Roma & Università Sapienza G. Organtini (Professore) 30% M. Raggi (RTDb) 50% (RN) 2.7 FTE Total 10.6 FTE 32+1 ricercatori +6 rispetto al 2016 Solo 1 post-doc 1 nuova dott. in corso d’anno Supporto tecnico INFN LNF (SPAS) C. Capoccia (Progettista meccanico) 50% E. Capitolo (Progettista meccanico) 50% (SELF) G. Corradi (Progettista Elettronico) 30% (OM) 2 mesi uomo II semestre (2016) INFN Roma M. Nuccetelli (20%) D. D’Angelo (20%) INFN Lecce G. Fiore (Tecnico e progettista) 30% INFN Lecce and Università Salento M. Corrado (Tecnico) 20% C. Pinto (Tecnico elettronico ) 20% CSN 1 - March 2017

External collaborations University of Sofia, prof. Venelin Kozhuharov and collaborators Memorandum of understanding signed, Bulgarian team associated to LNF Responsibility of scintillator veto detectors Participating to test-beam and preparation activities Obtained a 60K€ grant to participate into PADME in the next 3 years! MTA Atomki, Debrecen (Hungary), prof. Attila Krasznahorkay and collaborators Mutual agreement signed Exchange of researchers and students Lasts 3 years Two researchers joining April test beam Cornell University, CLASSE laboratory, prof. James Alexander and collaborators Mutual agreement being signed Joining test-beam and development activities on calorimeter Con il contributo del CSN 1 - March 2017

Seminars 2016 Chair of the PADME Editorial Board/Conference Committee: Stefania Spagnolo CSN 1 - March 2017

Conferenze 2016 19 contributi CSN 1 - March 2017

Construction and installation schedule CSN 1 - March 2017

2017: construction and installation 2018: commissioning and running Plan 2017-2018 2017: construction and installation Procurement of all components (excluding vacuum vessel): end of May Construction of calorimeter, small angle and veto detectors: by end of Oct. Installation: Nov. – end of year BTF closes from end of July to April 2018 for maintenance, building of the second line, installing PADME 2018: commissioning and running PADME aims at collecting 1x1013 positrons on target by the end of 2018 Approved running time 1 April – 31 July + 1 November to end of 2017. Assuming a 65% efficiency with 200 ns pulse length: 1.5*107s*49 pulses/s*20000 e+/pulse*0.65 = 1013 e+ on target CSN 1 - March 2017

Hand-shaking with DAFNE collisions* Running plan Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Procurement Construction Installation 2017 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Commissioning Physics Run 1 DAFNE collisions Run 1 2018 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Hand-shaking with DAFNE collisions* 2019 *Opportunities of making measurements in 2019 will depend on a number of factors: Length of SIDDHARTA-2 run vs. DAFNE-modified performance Running mode (injections frequency, duty cycle, etc.) … At 0th order, we would certainly like to extend the Run 1 statistics, as well as perform systematics checks, calibration or “special” runs, ancillary measurements, etc. CSN 1 - March 2017

Conclusions PADME experiment is extending the physics case to other dark sector models Dark Photons, ALPs searches & Fifth force Also extending the Collaboration Successful improvement of the bunch length obtained by LINAC+BTF staff Bunch length from 40ns  250ns Successful 5×5 prototype calorimeter beam-tests in July & November: Energy resolution s(E)/E = 2.0%/sqrt(E)+1.1% Mechanical design of the experiment advanced Details on glue, paint, support, etc. being refined Vacuum vessel defined Other main components in good shape: Veto detectors being finalized, also proceeding on the electronics Small angle first test successful Active diamond target practically ready (including readout electronics) Core 2016 used to procure all the components for calorimeter construction Core 2017 already secured by CSN1 in September meeting In line for starting physics data-taking at the beginning of 2018 CSN 1 - March 2017