Design study for a Helios-like spectrometer at LNS D. Santonocito – LNS User Meeting – 9/5/2017

Design study for a Helios-like spectrometer at LNS Study of nuclear structure direct reactions Elastic Scattering (sensitive to the density distribution of p,n) Inelastic Scattering (collectivity, B(E2),B(E3)) Single nucleon transfer reactions (single particle states, astrophysical process) Transfer of nucleons pair (pair correlations) Inverse kinematics: measurement of the light reaction partner Typical experimental problems: Low energy particles - identification Strong angular dependence Kinematical compression at large angles Low intensity beams (detection efficiency)

Helical orbit Spectrometer (HELIOS- Argonne ) : how it works ? Studio di fattibilità per uno spettrometro per particelle cariche leggere Helical orbit Spectrometer (HELIOS- Argonne ) : how it works ? Target inside the solenoid along the magnetic axis Light charged particles emitted from the target follow, in the magnetic field, helicoidal trajectories and are focused back on the magnetic axis: Tcyc = 2m/Bqe z = vparTcyc Detection through a position sensitive Si array. What we need to measure: Impact point z (Dx = 1 mm) Elab ToF (~ 1 ns) In an homogeneous field ToF = Tcycl Derived quantities: Particle identification m/q Ecm Qcm 2 m/q = (eB/2p) Tflight Ecm = Elab + 1/2mVcm –VcmeqBz/2p Qcm = arccos(qeBz-2pmVcm/(2p√2mElab +m2Vcm –mVcmqeBz/p) Schema HELIOS

Features of an helical orbit spectrometer From (Elab- Qlab) to (Elab – z) Particles identification Tcycl = 65.6 * A/qB (ns) (con A in amu, B in Tesla) B= 2 Tesla B = 3 Tesla Protoni 32.8 (ns) 21.9 (ns) d, Alfa2+ 65.6 (ns) 43.7 (ns) trizio 98.4 (ns) 65.6 (ns) Dimensions of the Solenoid Homogeneity of the field in the volume Size and shape of the detection array

Solenoid main features Parameters influencing the spectrometer acceptance : Magnetic field intensity (up to 5 Tesla) homogeneity (10-4) Radius (R) Lenght (L) Homogeneous field in the solenoid tipically restricted to a region with L ≈ 2R Max distance from the solenoid axis (cm) - protons Zimp of protons on solenoid axis ( B= 2T ) Max distance from the solenoid axis (cm) Zimp of protons on solenoid axis (cm) Emission Angle (deg) Emission angle (deg) LNS Solenoid dimensions: Radius=30 cm – Lenght = 200 cm

Shape of SOLE solenoid magnetic field per particelle cariche leggere Shape of SOLE solenoid magnetic field Sole in OPERA Field shape B=3T Z = 0 cross-section Shape of the field B=3T -100 -50 0 50 100 z (cm) 1 104 2 104 3 104 A. Calanna

Trajectories simulations in SOLE using OPERA Studio di fattibilità per uno spettrometro per particelle cariche leggere Trajectories simulations in SOLE using OPERA E= 2 MeV E= 6 MeV E= 2 MeV A. Calanna

Detector Array Effects: simulations HELIOS setup Si 1000 mm – 20 x 50 mm source posit.(0.5; 0; 0) cm A. Calanna

Preliminary results on spectrometer performances: simulations Studio di fattibilità per uno spettrometro per particelle cariche leggere Preliminary results on spectrometer performances: simulations Protons: E = 4 MeV, Q= 70° E = 4 MeV, Q= 70.5° Angolo ricostruito vs dimensione del beam spot A. Calanna

New Fragment separator Degrader Target where fragmentation occurs 2 - triplets 2 – doublets 2 - 70° dipoles 2 - 40° dipole courtesy A. Russo

Repositioning of SOLE solenoid in the CICLOPE area To build this line it is necessary to add Output Slit 2 – triplets 1- doublet 1 - 45° dipole CICLOPE Degrader Improvement in intensity: factor ≈ 4-5 with 100W factor ≈ 80 with 2 kW Target where fragmentation occurs courtesy A. Russo

Design study : next step Studio di fattibilità per uno spettrometro per particelle cariche leggere Design study : next step Detailed map of the magnetic field Simulations with the new map Test with a TANDEM beam and a limited detector array – elastic scattering Definition of the Silicon array (size – shape)

LNS Collaboration LNL Rosa Alba Giorgio Bellia Antonio Del Zoppo Alessia Di Pietro Pierpaolo Figuera Marcello Lattuada Concettina Maiolino Domenico Santonocito LNL Interest in this activity for the development of a new HELIOS-like spectrometer at LNL