High Density Jet Polarized Target Molecular Polarization Workshop Ferrara,Italy June

Marco Capiluppi Giuseppe Ciullo Marco Contalbrigo Paola Dalpiaz Ferretti Paolo Lenisa Michelle Stancari Marco Statera Istituto Nazionale di Fisica Nucleare Ferrara University A HIGH INTENSITY COLD SUPERCONDUCTING JET POLARIZED TARGET

How to increase the intensity of an ABS?  increase the acceptance  increase the input flow rate Consequences  Increased beam attenuation  lower magnet transmission?  lower dissociation?  pumping problems?

Why superconducting magnets? Calculated for cylindrical sextupoles using characteristics of NbTi wire currently availible NIM A (1985)

FLOW RATE AT TARGET POINT k number of selected states (1 or 2)  dissociation at nozzle exit Q in input flux f fraction of atoms entering the first magnet t magnet transmission, calculated with ray-tracing code. Depends on v drift and T beam A attenuation factor

NOVOSIBIRSK HERMES IUCF FERRARA

z(mm)d(mm) B pt (T) nozzle02 skimmer magnet magnet Target point Ferrara Preliminary Design Parameters  Nozzle Temperature: 60 K  Microwave Dissociator,  y0.65  Input flux: 3.0 mbar l/s  Superconducting magnets in superfluid He bath (1.8 K)

Transmission t  ray tracing program (SCAN) that calculates particle trajectories through the magnetic field  Based on code from CERN, expanded to calculate beam densities and particle loss distributions

Transmission t

Est. Time = 72 hours = 72 x (2-4) x 0.1 =18-36 hours  Cryogenic surfaces can adsorb 2-3 layers of molecules before saturating  The magnet cryostat serves as a cryopump, and the chamber pressure is determined by the vapor pressure of H 2 ( ~ mbar at 2 K) until the surface begins to saturate Rate of particle loss inside chamber (atoms/sec) Total cryogenic surface area Regeneration Time Estimate

ATTENUATION  Atoms of polarized jet collide with background molecules (rest gas scattering)  Atoms of polarized jet collide with each other (intrabeam scattering) number of collisions per unit volume per unit time Atomic jet density Density of attenuating particles Interaction cross section Relative velocity of attenuating particle 1 and jet atoms 2

number of collisions per unit volume per unit time rest gas scattering we can simpify this formula by assuming the densities are constant within the transverse area defining and observing that we obtain but integrating, we have finally : normally used formula

intrabeam scattering: a tentative approach DENSITY r-dependence DENSITY z-dependence

number of collisions per unit volume per unit time intrabeam scattering: tentative approach Density of the jet atoms at the point r,,z that will arrive at the target point Density of atoms at the point r,,z

ATTENUATION EVALUATION HERMES attenuation has been calculated as the ratio beteween the measured flow- rate and a theoretical flow-rate, obtained from the formula, using SCAN for t,and n=1 for f, with A=0

 beam fn1dfn1dfn1dfn1d S ib S rg (measured) S ib S rg Hermes x E (Koch thesis) 0.80E0.07 Nov x E0.06 >0.95(guess) 0.92E0.10 IUCF x E NIMA E0.07 Ferrara x E0.06 >0.90 >0.70 ATTENUATION ESTIMATES PRL (1989) PRA (1992) }

Ferrara Pumping System Requirements HermesIUCFFerrara S 1 (l/s) 2x22002x22002x2200 Q 1,jet (mbar l/s) x x x3.0 P 1 (mbar) 1.2x x10 -4 <2.4x10 -4 S 2 (l/s) 2x10002x22002x2200 Q 2,jet (mbar l/s) x x1.70 p 2 (mbar) 2.0x x10 -5 <1.0x10 -5 p 3 (mbar) <10 -7 Ferrara RGA attenuation will be no more than that of Hermes and IUCF

HermesNov.IUCFFerrara Q meas (atoms/s) 6.8x x x10 16 >58x10 16 Q th 7.4x x x x10 16 Q meas / Q th 0.92E E E0.09 S ib S rg 0.80E E E0.07 >0.70 tt cell i (atoms/cm 2 ) 0.9x x x x10 14 tt jet * d jet =1 cm 0.3x x x x10 12 d jet =2 cm d jet =2 cm 0.7x x x10 12 ~10x10 12 Comparison of measured and calculated intensities i Assuming HERMES cell geometry *Assuming beam cross section P jet cross section

HermesNov.IUCFFerrara  Q in (mbar l/s) (molec/s) (molec/s) x x x x10 19 B pt (T) d mag (cm) f  drift (m/s) 1953 ~ T beam (K) 25.0 ~ d tp (cm) t

THE SF-HELIUM CRYOSTAT TOTAL HEAT LOAD = 4.6 W CONSUMPTION < 5 l/h

THE COILS: ● NiTi wires ● 14X22 turns COIL CROSS SECTION 19.2 X 19.5 mm 2 ● Pole : steel with an iron core ● Height=232 mm outer diam.=109.1 mm ● R c = 76.6 to 85.9 mm SEXTUPOLE MAGNET

Coil Quench TRAINING POLE TIP 4.2 K MEASUREMENTS

DENSITY r-dependence DENSITY z-dependence