High Density Jet Polarized TargetHigh Density Jet Polarized Target

Molecular Polarization WorkshopMolecular Polarization Workshop

Ferrara,Italy 16-18 JuneFerrara,Italy 16-18 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 How to increase the intensity of an ABS?ABS?

increase the acceptanceincrease the acceptance increase the input flow rateincrease the input flow rate

Consequences

Increased beam attenuationIncreased beam attenuation lower magnet transmission?lower magnet transmission? lower dissociation?lower dissociation? pumping problems?pumping problems?

2

2

m

Bpt

2

2

m

Bpt

2

ptpt r

rBB

rr

B

r

BF

pt

pt2

2

Why superconducting magnets?

Calculated for cylindrical sextupoles using characteristics of NbTi wire currently availible

NIM A240 229 (1985)

FLOW RATE AT TARGET POINTFLOW RATE AT TARGET POINT

AtfQk

Q inout 124

kk number of selected states (1 or 2) number of selected states (1 or 2)

dissociation at nozzle exitdissociation at nozzle exit

QQinin input flux input flux

ff fraction of atoms entering the first magnet fraction of atoms entering the first magnet

tt magnet transmission, calculated with ray-tracing code. Depends on v magnet transmission, calculated with ray-tracing code. Depends on vdrift drift and Tand Tbeambeam

AA attenuation factor attenuation factor

NOVOSIBIRSK

HERMES

IUCF

FERRARA

z(mm)z(mm) d(mm)d(mm) BBptpt (T) (T)

nozzlenozzle 00 22

skimmerskimmer 1515 6.4-9.06.4-9.0

magnet 1magnet 1 57-45657-456 40 -10040 -100 6.0-1.26.0-1.2

magnet 2magnet 2 756-1056756-1056 100-80100-80 3.4-6.03.4-6.0

Target pointTarget point 12501250 2020

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 Transmission tt

ray tracing program (SCAN) that ray tracing program (SCAN) that calculates particle trajectories through the calculates particle trajectories through the magnetic fieldmagnetic field

Based on code from CERN, expanded to Based on code from CERN, expanded to calculate beam densities and particle loss calculate beam densities and particle loss distributions distributions

Transmission Transmission tt

Transmission Transmission tt

Est. Time = 72 hours QQ

AA

FE

NOV

NOV

FE = 72 x (2-4) x 0.1

=18-36 hours

A

Qtime

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 H2 (~10-15 mbar at 2 K) until the surface begins to saturate

Rate of particle loss inside chamber (atoms/sec)

Total cryogenic surface area

Regeneration Time EstimateRegeneration Time Estimate

ATTENUATIONATTENUATION Atoms of polarized jet collide with background Atoms of polarized jet collide with background

moleculesmolecules ((rest gas scatteringrest gas scattering)) Atoms of polarized jet collide with each other Atoms of polarized jet collide with each other

(intrabeam scattering)(intrabeam scattering)

number of collisions per unit volume per unit time

Atomic jet density

Density of attenuating

particlesInteraction cross

sectionRelative velocity of attenuating

particle 1 and jet atoms 2

21nndVdt

drel

2nrel 1n

21nndVdt

drel

beamrel rg

rg

kT

pn 1

number of collisions per unit volume per unit timenumber of collisions per unit volume per unit time

rest gas scattering

21 HH

we can simpify this formula by assuming the densities are constant within the we can simpify this formula by assuming the densities are constant within the transverse area transverse area

21nnAdtdz

d

21nndt

dz21Anndz

dz

d defining 2AnN

and observing that dz

ddN

NndzdN 1we obtain

butrg

rg

kT

pn 1

1ndzN

dN

rg

rg

kT

pdz

N

dN

dpkTrg

zrg

eNzN

0

0)(

integrating, we have finally :

normally used formula

2n 1nz

z

intrabeam scattering: a tentative approach

DENSITY r-dependenceDENSITY r-dependence DENSITY z-dependenceDENSITY z-dependence

number of collisions per unit volume per unit timenumber of collisions per unit volume per unit time 21nndVdt

drel

intrabeam scattering: tentative approach

FWHMrel 2 11 HH

21nnAdzdt

d

Adtnndz

d21

dzNndz

d

beam

1dz

ddN

dznN

dN

beam

1

dnz

beameNzN

0 1

0)(

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

rel

dn

ibib

z

beameN

zNS

0 1

0

)(

dpkTrg

rg

zrg

eNzN

0

0)(

ATTENUATION EVALUATIONATTENUATION EVALUATION

dpkTrgrg

rg

zrg

eN

zNS

0

0

)(

dn

ib

z

beameNzN

0 1

0)(

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

AtfQk

Q inout 124

.

1th

measout

HERMES Q

QA

rgibSSA1

10.088.01 HERMESA

beambeam ffnn11dd SSibib

SSrgrg

(measured)(measured)SSib ib SSrgrg

HermesHermes 0.290.29 0.90x100.90x101818 0.880.88EE0.060.06 0.910.91(Koch thesis)(Koch thesis)

0.800.80EE0.070.07

Nov.Nov. 0.320.32 0.22x100.22x101818 0.970.97EE0.060.06 >0.95>0.95(guess)(guess)

0.920.92EE0.100.10

IUCFIUCF 0.350.35 0.65x100.65x101818 0.890.89EE0.060.06 0.900.90NIMA NIMA 336336 410 410

0.800.80EE0.070.07

FerraraFerrara 0.320.32 1.03x101.03x101818 0.850.85EE0.060.06 >>0.900.90 >>0.700.70

ATTENUATION ESTIMATESATTENUATION ESTIMATES

21811 1025.050.0, mHH PRL 63 750 (1989)

PRA 46 6959 (1992)}

Ferrara Pumping System Requirements

HermesHermes IUCFIUCF FerraraFerrara

SS1 1 (l/s)(l/s) 2x22002x2200 2x22002x2200 2x22002x2200

QQ1,jet 1,jet (mbar l/s)(mbar l/s) 0.9900x1.50.9900x1.5 0.9835x1.70.9835x1.7 0.9484x3.00.9484x3.0

PP11(mbar)(mbar) 1.2x101.2x10-4-4 3.4x103.4x10-4-4 <2.4x10<2.4x10-4-4

SS2 2 (l/s)(l/s) 2x10002x1000 2x22002x2200 2x22002x2200

QQ2,jet 2,jet (mbar l/s)(mbar l/s) 0.0068x1.50.0068x1.5 0.0280x1.70.0280x1.7 00

pp2 2 (mbar)(mbar) 2.0x102.0x10-5-5 6.5x106.5x10-5-5 <1.0x10<1.0x10-5-5

pp3 3 (mbar)(mbar) 1010-6-6 -10 -10-7-7 1010-6-6 -10 -10-7-7 <10<10-7-7

Ferrara RGA attenuation will be no more than that

of Hermes and IUCF

HermesHermes Nov.Nov. IUCFIUCF FerraraFerrara

QQmeasmeas(atoms/s)(atoms/s) 6.8x106.8x101616 7.8x107.8x101616 6.7x106.7x101616 >58x10>58x101616

QQthth 7.4x107.4x101616 8.1x108.1x101616 7.5x107.5x101616 73.1x1073.1x101616

QQmeasmeas//QQthth 0.920.92EE0.090.09 0.960.96EE0.140.14 0.890.89EE0.090.09

SSibibSSrgrg 0.800.80EE0.070.07 0.920.92EE0.100.10 0.800.80EE0.070.07 >0.70>0.70

ttttcellcellii (atoms/cm(atoms/cm22)) 0.9x100.9x101414 0.5x100.5x101414 0.9x100.9x101414 4.0x104.0x101414

ttttjetjet** ddjetjet=1 cm=1 cm 0.3x100.3x101212 0.5x100.5x101212 0.3x100.3x101212 3.0x103.0x101212

ddjetjet=2 cm=2 cm 0.7x100.7x101212 1.1x101.1x101212 1.2x101.2x101212 ~10x10~10x101212

Comparison of measured and calculated intensities

iiAssuming HERMES cell geometry *Assuming beam cross section Assuming HERMES cell geometry *Assuming beam cross section PP jet cross section jet cross section

HermesHermes Nov.Nov. IUCFIUCF FerraraFerrara

0.800.80 0.900.90 0.750.75 0.650.65

QQin in (mbar l/s)(mbar l/s)

(molec/s)(molec/s)

1.51.5

3.8x103.8x101919

0.60.6

1.5x101.5x101919

1.71.7

4.3x104.3x101919

3.03.0

7.5x107.5x101919

BBpt pt (T)(T) 1.51.5 3.23.2 1.51.5 6.06.0

ddmag mag (cm)(cm) 0.860.86 1.41.4 1.041.04 4.04.0

ff 0.00550.0055 0.01340.0134 0.00970.0097 0.02110.0211

drift drift (m/s)(m/s) 19531953 ~~17501750 14941494 12001200

TTbeam beam (K)(K) 25.025.0 ~~30.030.0 16.516.5 15.015.0

ddtp tp (cm)(cm) 1.01.0 2.02.0 1.01.0 2.02.0

tt 0.450.45 0.440.44 0.240.24 0.350.35

ATvtfQk

Q beamdriftn

inout 1,cos24

THE SF-HELIUM CRYOSTAT

TOTAL HEAT LOAD = 4.6 WHe @2K CONSUMPTION < 5 l/h

THE COILS:● NiTi wires● 14X22 turns COIL CROSS SECTION 19.2 X 19.5 mm2

● Pole : steel with an iron core ● Height=232 mm outer diam.=109.1 mm ● R

c= 76.6 to 85.9 mm

SEXTUPOLE MAGNET

300

350

400

450

500

550

I [A

]

bobina A

bobina B

bobina C

bobina D

bobina E

bobina F

Coil

Coil

Coil

Coil

Coil

Coil

Quench

TRAINING

POLE TIP FIELD @ 4.2 K

coil 5 5 2 5 6 3 1 4 5 2 4 6

I [A] 357 456 452 492 490 494 496 500 515 518 513 517

MEASUREMENTS

DENSITY r-dependenceDENSITY r-dependence DENSITY z-dependenceDENSITY z-dependence