13/01/2019 Final Results of ACLIP Experiment Carlo De Martinis, Dario Giove, Antonio Rainò, Vincenzo Variale, Maria Rosaria Masullo, Vittorio GiorgioVaccaro Collaborazione fra le sezioni di Bari, Milano e Napoli , il Politecnico di Bari, l’Università di Milano e l’Università di Napoli “Federico II” e la ditta e2v di Chelmsford (U.K.) 1

PALME project CYCLOTRON : beam of 30 MeV The project PALME is relevant to the design of a proton linac from 30 to 62 MeV The ACLIP experiment is relevant to fabrication and tests of the first two modules from 30 to 41 MeV. CYCLOTRON : beam of 30 MeV PALME : LINAC post-accelerator from 30 MeV to 62 MeV LIBO : booster from 62 MeV to 240 MeV

PALME Schematic Structure Q=quadrupoles RF=radiofrequency

Side-Coupled LINAC Accelerator 13/01/2019 Because of compactness only one cavity is directly fed. The power flows in all the others via the slots (the borders between white and yellow). Beam Coupling cavities Accelerating cavities Solid copper 4

For the optimization of the linac design: Goal of the design For the optimization of the linac design: simplify the manufacturing and reduce its cost maximise the mean accelerating gradient per unit power (maximise Shunt Impedance) maximise the transmittance (in order to minimize the current required from the cyclotron) verify that the beam losses are compatible with safety requirements adjust the duty-cycle in order to keep the thermal rise inside a range acceptable for the tuning

L’innovazione in ACLIP a confronto con il disegno standard Secondo il disegno standard (figura a sinistra), ogni mattonella è fabbricata in modo da mostrare mezza cavità di accoppiamento su di una faccia e mezza cavità di accelerazione sull’altra. Una configurazione di questo tipo è altamente inefficiente per un fascio di 30 MeV ed è impraticabile per un ciclotrone di 18 MeV. L’innovazione consiste in una nuova configurazione (figura a destra) Giallo intenso: facce di brasatura Giallo chiaro: facce esterne Tratteggio: tagli Bianco: parti interne

Elementary Structure: Back to Back Accelerating Cavity (BBAC) 13/01/2019 7

L’innovazione in ACLIP a confronto con il disegno standard VANTAGGI DELL’INNOVAZIONE Poiché la mattonella è equivalente a due del tipo standard, i costi di lavorazione sono ridotti e le tolleranze di fabbricazione possono essere rilassate Poiché il setto tra due cavità acceleranti adiacenti non è più ottenuto col posizionamento dorso a dorso di due mattonelle, la lavorazione è semplificata ed il setto può essere ridotto senza pregiudizio per la brasatura A causa della riduzione della dimensione del setto, si ha una riduzione della potenza dissipata a parità di campo elettrico accelerante (aumento della cosiddetta Shunt Impedance) Per l’aumento della dimensione delle cavità e per la asimmetria nella loro partizione c’è spazio sufficiente per l’inserimento di sintonizzatori

ONE MODULE 9

L’ESPLOSO 10

TRANSMITTANCE The partial transmittance, Tp, is the ratio between the amounts of extracted useful particles (within the energy spread useful for the therapy) and injected ones. The total transmittance, Tt, relevant to the total amount of extracted particles. For a continuous incoming beam optimum transmittance with fs =-23° @62MeV The optimum linac configuration: 12 tanks, composed by 12 accelerating cavities Lquads = 33.5 mm ---- kQ = 195 T/m Tt = 12% ------ Tp (@ 1MeV) = 11.6%

The activation: preliminary results 13/01/2019 The activation: preliminary results During the PALME design the activation process in the structure has been studied in order to evaluate the related dose rate. The dynamics analysis suggests us to restrict our studies to the process of interaction of the primary 30 MeV beam with the copper RF cavities. To study the process we adopted a quite conservative scenario. The maximum amount of dose rate at saturation is given by Zn-63, but because of its short half life, it becomes quickly negligible. One may easily calculate the total dose rate, after 3.0 hs from the beam stop event; this falls to a value of the order of 100 mGy/h which is compatible with the possibility of carrying out a maintenance procedure. Furthermore this dose is compatible with very short emergency intervents (less then five minutes) even just after the beam-stop.

PALME Temperature distribuition of the subset

Il primo modulo di PALME appena sfornato (sic!) ACLIP Il primo modulo di PALME appena sfornato (sic!)

Assembly of the first module at CERN

Power tests at e2v (Chelmsford)

Power tests at e2v (Chelmsford) Remarks The goal of ACLIP experiment is to demonstrate the acceleration feasibility using a Side Coupled Linac, fed at 3GHz, which accepts a 30MeV proton beam. In order to discriminate the accelerated protons, the mean gradient in cavities has been stressed up 20 MV/m. This implies that, for the first module, the needed input power is 2.7 MW. It is worth of note that in the final design, for the first module, the accelerating gradient has been set at 16 MV/m, implying a reduction of the input power at 1.73 MW.

Power tests at e2v (Chelmsford) f=2999.3 MHz, Pulse length 5ms @75Hz Direct Power 1.5 MW

Power tests at e2v (Chelmsford) f=2999.3 MHz, Pulse length 7ms @75Hz Direct Power 3 MW

Power tests at e2v (Chelmsford) f=2999.3 MHz, Pulse length 5ms @20Hz Direct Power 4 MW High X-ray rate of production

Conclusions 1 At low rep. rate, the reflected power ranges between 20% and 10%, constantly decreasing between consecutive measuremets. The module has been tested up to 4.0 MW input power. For 5ms pulse length and 3.0 MW input power, the rep. rate was increased up to 150Hz. An increase of reflected power was detected and electric discharges started to appear at 150 Hz. The performance of the module is more then sufficient to carry out the acceleration tests in Catania foreseen for late Spring-early Summer. Indeed we need very low rep. rate for this experiment.

Conclusions 2 For what concerns the final design, the indications are quite encouraging since the performances of the module amiliorate with decreasing power. Furthermore, taking into account that the conditioning was very poor for the limited temporal length of the slot allotted by e2v, we may quite confidently foresee that good performances can be easily reached at: rep. rate 120 Hz; pulse length 7 ms; available power 1.73 MW With these parameters we may obtain a mean current of 8 nA.

GRAZIE DELLA ATTENZIONE FINE GRAZIE DELLA ATTENZIONE 13/01/2019Napoli, 23 Marzo 2007