PERSPECTIVES FOR HIGHLY POLARIZED ION SOURCES DEVELOPMENT

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15 Νοε 2013 (πριν από 3 χρόνια και 4 μήνες)

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PERSPECTIVES FOR HIGHLY
POLARIZED ION SOURCES
DEVELOPMENT


Vadim Dudnikov,

Muons, Inc., Batavia, IL USA



The XVth International Workshop on Polarized Sources, Targets and
Polarimetry (PTSP 2013) the University of Virginia, Charlottesville, USA,
September 2013

Muons, Inc.

1

OUTLINE

Features of an Universal ABP ion source are discussed.

The main innovation of this approach is the strong suppression of
parasitic generation of unpolarized H
-
/D
-

ions by using novel
designs of the dissociator, plasma generator, and surface
-
plasma
ionizer, extraction system, which prevent adsorption and
depolarization of particles from the polarized atomic beam. The
same system with some modifications can be capable of
producing positive and negative ion beams of different species
including polarized and unpolarized H
-
, D
-
, H
+
, D
+
, 3He, and Li.

Production of polarized 3He
-

ion beam with intensity ~ mA will be
discussed

INTRODUCTION

*High beam polarization degree is essential to the scientific
productivity of a collider.

*A figure
-
8 shape of booster and collider rings is an optimized
solution to preserve ion beam polarization by avoiding spin
resonances during acceleration and to ensure energy
independence of spin tune.

*In addition, a figure
-
8 shape ring is the only practical way for
accelerating and storing polarized deuterons at a medium energy
range. If there is no depolarization during acceleration and
storage, the final beam polarization is determined by the initial
polarization at extraction from the ion source.

* Ion sources with performances exceeding those achieved today
is a key requirement for the development of the next generation
high
-
luminosity high
-
polarization colliders.

Budker Institute of
Nuclear Physics


www.inp.nsk.su

Novosibirsk State
University
www.nsu.ru

Requirements to the polarized source.


Requirement to ion sources intensity was decreased for many
orders by development of
charge exchange injection,
capable to
accumulate beams during tens thousand turns.


High intensity ~ 5

10
11

H
-
/pulse at 200 MeV after the Linac. At
booster beam intensity acceptances are limited by about 1

10
11

protons/bunch. The intensity excess can be used to reduce
transversal and longitudinal beam emittances by a strong
dynamical collimation in the Booster.


Highest possible polarization is required to reduce a
systematical and statistical errors in polarization experiments.
Double spin asymmetry statistical error is proportional to ~
1/sqrt(L P
4)
, therefore a 5% polarization increase in the source
(or 5% polarization losses decrease in booster and EIC

is
effectively equivalent to 30% increase in the data taking time.



Beam intensity and polarization must be equal at spin
-
reversal
and from pulse to pulse.


Δ
I/I <10
-
3

and
Δ
P/P < 1% need be reached.


6

Major Components of MEIC Ion Complex

The MEIC ion beam polarization design requirements are:


High polarization (over 70%) for protons or light ions (
d
, 3He++,
and possibly 6Li+++).


Both longitudinal and transverse polarization at all IPs.


Sufficiently large lifetime to maintain high beam polarization.


Spin flipping at a high frequency.

to high
-
energy

collider ring

Ion

source

SRF linac

Prebooster

(accumulator ring)

Large booster

Medium
-
energy collider ring

Cooling

Cooling

V. Morozov Report

Existing Sources Parameters


Universal Atomic Beam Polarized Sources
(most promising,
less expensive for repeating):


IUCF/INR CIPIOS:

Pulse Width Up to 0.5 ms (Shutdown
8/02);


Peak Intensity H
-
/D
-

2.0 mA/2.2 mA; Max Pz/Pzz 85% to
95%; Emittance (90%) 1.2 π·mm·mrad.


INR Moscow:

Pulse Width > 0.1 ms (Test Bed since 1984);


Peak Intensity H+/H
-

11 mA/4 mA; Max Pz 80%/95%;


Emittance (90)% 1.0 π·mm·mrad/ 1.8 π·mm·mrad;


Unpolarized H
-
/D
-

150/60 mA


SPI Dubna up to 10 mA for D+ ( H+) [under commissioning]

The
D+ polarization will be up to 90% of the maximal vector
(
±
1) &tensor (+1,
-
2) polarization


OPPIS/BNL:

H
-

only; Pulse Width 0.5 ms (in operation);


Peak Intensity >1.6 mA; Max Pz 85% of nominal


Emittance (90%) 2.0 π·mm·mrad.


Muons, Inc.

First polarized
-
proton sources described at the

INTERNATIONAL SYMPOSIUM ON POLARIZATION


PHENOMENA OF NUCLEONS

Basel, July 1960

Sources of Polarized Ions


a review of early work

SOURCES OF POLARIZED IONS

BY W. HAEBERLI

ANNUAL

REVIEW

OF NUCLEAR SCIENCE


Vol. 17, 1967

The status 40 years ago:

W. Haeberli,
PSTP
-
2007,
BNL, USA

Method based on 1968 proposal (NIM
62

p. 335)

s

= 22x10
-
16
cm
2
at 2keV
-
>
100x10
-
16
cm
2

at 10eV





A.S. Belov et al. (INR
-
Moscow)
-

20 yrs development work

Intense beam of unpolarized D
-

from

deuterium surface
-
plasma ionizes an atomic

Beam (2x10
17

H
0

/
sec puled)

Pulsed
4 mA H
-


95% Polarization



W. Haeberli, PSTP
-
2007, BNL, USA


OPPIS
: Zelenski, Mori et al.

20 years of development



1.6 mA H
-


85
-
90% Polarization


with new proton source
20
-
50mA

possible

L.W. Anderson (Wisconsin)
-

optically pumped Na as donor (1979)





3 keV H
+

POLARIZED

H
+
AND H
-

DONOR:

OPTICALLY PUMPED

CHARGE
EXCHANGE

B

B

“SONA”

TRANSITION

W. Haeberli, PSTP
-
2007, BNL, USA

A. Belov & V. Derenchuk:
IUCF/INR CIPIOS

developers

ABPIS with Resonant Charge Exchange
Ionization and Surface
-
Plasma D
-

generation

Muons, Inc.


INR Moscow


H
0
↑+ D+

H+
↑+ D
0


D
0
↑+ H+

D+
↑+ H
0


σ~ 5 10
-
15
cm
2


H
0
↑+ D−

H
−↑+ D
0


D
0
↑+ H−

D
−↑+ H
0


σ~ 10
-
14
cm
2


A. Belov, DSPIN2009


Main Systems of INR ABPIS with
Resonant Charge Exchange Ionization

Muons, Inc.


Atomic Beam Polarized Ion source

In the ABS, hydrogen or deuterium atoms are formed by dissociation of molecular gas,
typically in a RF discharge. The atomic flux is cooled to a temperature 30K
-

80K by
passing through a cryogenically cooled nozzle. The atoms escape from the nozzle orifice
into a vacuum and are collimated to form a beam. The beam passes through a region
with inhomogeneous magnetic field created by sextupole magnets where atoms with
electron spin up are focused and atoms with electron spin down are defocused.

Nuclear polarization of the beam is increased by inducing transitions between the spin
states of the atoms. The transition units are also used for a fast reversal of nuclear spin
direction without change of the atomic beam intensity and divergence. Several schemes
of sextupole magnets and RF transition units are used in the hydrogen or deuterium ABS.
For atomic hydrogen, a typical scheme consists of two sextupole magnets followed by
weak field and strong field RF transition units. In this case, the theoretical proton
polarization will reach Pz = _1. Switching between these two states is performed by
switching between operation of the weak field and the strong field RF transition units. For
atomic deuterium, two sextupole magnets and three RF transitions are used in order to
get deuterons with vector polarization of Pz = _1 and tensor polarization of Pzz= +1,
-
2

Different methods for ionizing polarized atoms and their conversion into negative ions
were developed in many laboratories. The techniques depended on the type of
accelerator where the source is used and the required characteristics of the polarized ion
beam (see ref. [2] for a review of current sources).

For the pulsed atomic beam
-
type polarized ion source (ABPIS) the most efficient method
was developed at INR, Moscow [3
-
5]. Polarized hydrogen atoms with thermal energy are
injected into a deuterium plasma where polarized protons or negative hydrogen ions are
formed due to the quasi
-
resonant charge
-
exchange reaction:

Ionization of polarized atoms

Resonant charge
-
exchange reaction is charge
exchange between atom and ion of the same
atom: A
0

+ A
+

→A
+

+ A
0

•cross
-
section is of order of 10
-
14

cm
2

at low
collision energy

•Charge
-
exchange between polarized atoms
and ions of isotope relative the polarized
atoms to reduce unpolarized background

•W. Haeberli proposed in 1968 an ionizer with
colliding beams of ~1
-
2 keV D
-

ions and
thermal polarized hydrogen atoms:


H
0
↑+ D


H

↑+ D
0


Destruction of negative hydrogen
ions in plasma


H


+ e


H
0

+ 2e
s

~ 4

10
-
15

cm
2


H


+ D
+



H
0

+ D
0
s

~ 2

10
-
14

cm
2


H


+ D
0



H
0

+ D



s

~ 10
-
14

cm
2


H


+ D
2



H
0

+ D
2

+ e
s

~ 2

10
-
16

cm
2


H


+ D
0



HD
0

+ e
s

~ 10
-
15

cm
2


Details of ABIS with Resonant
Charge Exchange Ionization

Resonance charge exchange ionizer with
two steps surface plasma converter

*Jet of plasma is guided
by magnetic field to
internal surface of cone;

*fast atoms bombard a
cylindrical surface of
surface plasma
converter initiating a
secondary emission of
negative ions increased
by cesium adsorption.

*An electron blocker
collects plasma
electrons, decreases
electron extraction and
H
-
destruction

INR ABPIS:

Oscilloscope Track of Polarized H
-

ion

Polarized H
-

ion
Current 4 mA
(vertical scale
-
1mA/div)

Unpolarized D
-

ion
current 60 mA
(10mA/div)

Parasitic H
-

current without
polarized H
atomic beam


A. Belov

Probability of H
-

emission as function of
work function (cesiation effect)

The surface work function decreases
with deposition of particles with low
ionization potential and the probability
of secondary negative ion emission
increases greatly from the surface
bombarded by plasma particles.

Dependence of work function on surface
cesium concentration for W crystalline
surfaces and relative yield Y of H
-

secondary emission for W surface index
(111), right scale


Muons, Inc.

20

Schematic of negative ion formation


on the surface (
φ
>S)



(formation of secondary ion emission;
Michail Kishinevsky)

Sov. Phys. Tech. Phys, 45 (1975))




Affinity lever S is lowering by image
forces below Fermi level during
particle approaching to the surface;



Electron tunneling to the affinity
level;



During particle moving out of
surface electron affinity level S go
up and the electron will tunneling
back to the Fermi level;



Back tunneling probability w is high
at slow moving (thermal) and can be
low for fast moving particles;
Ionization coefficient
β
-

can be high
~0.5 for fast particles with S<~
φ

Coefficient of negative ionization as function of work
function and particle speed

Kishinevskiĭ M
E,
[Sov. Phys.
Tech. Phys.
,
48

(1978), 773;
23

(1978), 456

Production of surfaces with low work
function (cesium coverage)

The surface work function
decreases with deposition of
particles with low ionization
potential (CS) and

the probability
of secondary
negative ion emission increases
greatly from the surface
bombarded by plasma particles.

Muons, Inc.

23

Dependences of desorption
energy H on surface
Cesium concentration N
for different W crystalline
surfaces: 1
-
(001); 2
-
(110);
3
-
(111); 4
-
(112).

The work function in the case of cesium adsorption in
dependence upon the ratio of sample temperature T to
cesium
-
tank temperature TCs for collectors of 1) a
molyb
denum polycrystalline with a tungsten layer on
the surface, 2) (110) molybdenum, 3) a molyb
denum
polycrystalline, and 4) an LaB6 polycrystalline.

Probability of particles and energy reflection for
low energy H particles


Influention of Cs+H co
-
adsorption to H
-
/D
-

reflection

*Conversion Ho/H
-

by Scattering
on W+Cs+H surface

*Desorption of H
-

from W+Cs+H
surface

*Important for suppression of H
-
/D
-

production from depolarized
components

P. W. van Amersfoort, et al.,

J. Appl. Phys. 59, 241 (1986);

The low WF is need to support in dense plasma. It is
necessary to inject some Cs (as shown in SNS SPS)

H
-

beam
intensity is
raised after
casiation but
decayed
exponencialli
during
operation

Fortunately, condition of “activation” was found in SNS SPS for
efficient operation with very low Cs injection (mg/weeks, instead
mg/hour) This “gift of nature” is not understudy in full scale an is
not reproducible in different SPS. (Need further development)


At firs it was hypothesed, that a better cleaning of
electrodes surface increases the binding energy and
decrease Cs evaporation and sputtering.

But it was recognized that a converter surface is deposited
by dark film. Not only cleaning but deposition are
important for optimal cesiation. Clean H plasma!


Distributions of elements on the converter cone surface.
Sputter time in minutes. 20 min of sputtering is ~20
nanometers

Carbon deposition
and Cs
intercolation can
be important for
stable SPS
operation with low
Cs consumption

Schematic diagram of IUCF ABPIS with resonant
charge exchange ionization (was tested for long
time injection of D
-
)


The pulsed polarized negative ion source (CIPIOS) multi
-
milliampere beams
for injection into the Cooler Injector Synchrotron (CIS).

Schematic of ion source and LEBT showing the entrance to the RFQ.

The beam is
extracted from the
ionizer toward the
ABS and is then
deflected
downward with a
magnetic bend and
towards the RFQ
with an
electrostatic bend.


This results in a
nearly vertical
polarization at the
RFQ entrance.


Belov, Derenchuk, PAC
2001

Components of IUCF ABPIS (sextupole, ionization solenoid,
RF dissociator, bending magnet, Arc discharge plasma
source,

Schematic of JINR ABPIS (SPI) with resonant
charge exchange ionization (polarized H+,D+)

General view of JINR ABPIS (SPI) with resonant
charge exchange ionization (polarized H+,D+)

Arc discharge ion source with expansion of plasma


jet (Dimov BINP 1962)

Plasma density up to 10 **15 cm
-
3; Ionization 99.9 %, dissociation 99%, transverse ion
temperature 0.005 eV; multi slit extraction (H+, He+ ~2A); H
-
~16 mA (H2); D
-
~100 mA
(Na); He
-
~10 mA (Na). 1
-
gas valve; 2
-
triggering; 3 cathode; 4
-
barier washe; 5
-
woshed
channel; 6
-
anode; 7
-
extracrion holder; 9, 10

extraction grids.

Long pulse arc
-
discharge plasma generator with LaB
6

cathode (heating prevents polarized particles adsorption
and desorption as negative ions)

Version with one LaB
6

disc

Version with several LaB
6

discs

Metal
-
ceramic discharge channel is developed


Can be lower gas density, Higher He++ beam current

Fast, compact gas valve, 0.1ms, 0.8 kHz

1

-
current feedthrough;

2
-

housing;
3
-
clamping

screw;
4
-
coil;
5
-

magnet

core;
6
-
shield;
7
-
screw;

8
-
copper insert;
9
-
yoke;

10
-
rubber washer
-

returning springs;

11
-
ferromagnetic plate
-

armature;
12
-
viton stop;

13
-
viton seal;
14
-
sealing


ring;
15
-
aperture;

16
-
base;
17
-
nut.

Fast, compact Cesium Supplies

*Cesium oven with cesium
chromate pellets
(Cs2CrO4+Ti) and press
-
form
for pellets preparation.


Cesium oven with BiCs2 alloy



*Cesium oven with Cs getters


(Cs2ChO4 +Zr+Al+…)


Highly transparent fine precise extraction system

A four
-
electrode multislit extraction consists of

three multi
-
wire grids and a fourth cylindrical grounded
electrode. The grids are made of 0.2 mm molybdenum
wire. The spacing between wires is 1.0 mm. The wires
are positioned on the mounting electrodes by precisely
cut grooves and fastened by point welding. The mutual
grid alignment accuracy is better than 0.02 mm.

The gap between the first and second grids is 1.0 mm,
the second and third grids

2.0 mm, the third and
fourth

2.0 mm.

This design increases the beam brightness relative two
grids system.

BNL
Polarimeter
, 1.2 10**17 p/s


The H
-
jet polarimeter includes
three major parts: polarized Atomic
Beam Source (ABS), scattering
chamber, and Breit
-
Rabi
polarimeter.


The polarimeter axis is vertical and
the recoil protons are detected in
the horizontal plane.



The common vacuum system is
assembled from nine identical
vacuum chambers, which provide
nine stages of differential pumping.


The system building block is a
cylindrical vacuum chamber 50 cm
in diameter and of 32 cm length
with the four 20 cm (8.0”) ID
pumping ports
.



19 TMP , 1000 l/s pumping speed
for hydrogen.

Schematic of ABPIS


The PABIS includes three major
parts: polarized Atomic Beam
Source (ABS), ionizer, beam
formation/separation,and Lemb
polarimeter.


The PABIS axis is vertical and ion
beam is bended to the horizontal
plane.



The common vacuum system is
assembled from 5 identical
vacuum chambers of ABS, which
provide 5 stages of differential
pumping.


The system building block is a
cylindrical vacuum chamber 50 cm
in diameter and of 32 cm length
with the four 20 cm (8.0”) ID
pumping ports
.



10 TMP , 1000 l/s pumping speed
for hydrogen+ 2.2 kl/s+cryopump

Further ABPIS development

*Intensity and polarization of polarized beams produced by ABPIS
can be improved by further optimization of ABS and ionization
technique.

*In particular, atomic beam formation should be studied to
overcome limitations connected with a beam
-
skimmer
interference.

*Sextupole magnet system parameters should be optimized taking
into account results of optimization of atomic beam formation
system.

*With these improvements pulsed polarized H
-
, (D
-
) ion beams
with peak intensity of ~10 mA (~ 20 mA for H+ and D+ ions) and
polarization of ~ 95% seems to be possible

INJECTION OF BACKGROUND GAS AT DIFFERENT



POSITION

ATTENUATION OF THE BEAM IS

DEPENDENT FROM THE POSITION

OF THE GAS INJECTIOJN

NOT MANY EXPERIMENTAL DATA

AVAILABLE

D.K.Toporkov, PSTP
-
2007, BNL, USA


Fine art of intense atomic beam formation (intensity limitation)

Cryogenic Atomic Beam Source

Liquid nitrogen

Cryostat

Two group of magnets


S1, S2

(tapered magnets) and
S3, S4, S5

(constant radius) driven independently,
200

and
350

A
respectively; Bt~ 4.8 T.


BINP atomic beam source with superconductor sextupoles

Focusing magnets

Permanent magnets

B=1.6 T

Superconducting

B=4.8 T


DW = p*a
2

= p*m*B/kT



B = 1.6 T DW ~ 1.5*10

2

獲=

a ~ 0.07
牡r




B = 4.8 T DW ~ 4.5*10

2
=


a ~ 0.21
牡r




Polarized Gas Target, ABS and LDS

Flux of polarized deuterium atoms injected into the cell at/sec.


Magnetic poletip field of superconducting magnets up to
4.8

T

P
zz
=0.4, target thickness viewed by the detector 8x10
13
at/cm
2

16
8.2*10
13x14x400 mm

Inner diam. 44 mm

Dmitri Toporkov Summary of the 10
th

Workshop on

SPIN2004 Polarized Sources and Targets PST200
3

Yuri Shestakov

(BINP)

High Density Polarized Deuterium Gas Target for the VEPP
-
3


Electron Storage Ring


3
He
++

Ion source with Polarized
3
He Atoms and Resonant Charge
Exchange Ionization

A.S. Belov, PSTP
-
2007, BNL, USA



Plans of ABPIS development

Review of existing versions of ABPIS components for
choosing an optimal combinations;

General design of optimal ABPIS;

Estimation availability of components and materials:

Estimate of project cost and R&D schedule;

Establish cooperaion:

INR, A. Belov

BINP, D. Toporkov, V. Davydenko,

BNL, A. Zelenski,

IUCF, Dubna, V. Derenchuk, V. Fimushkin,

COSY/Julich, R. Gebel.


3He
-

sources development

* For alpha particles diagnostics in fusion plasma of ITER under
development He
-

ion source with current ~10 mA and Energy ~1
MeV (He+ current ~3 A with low emittance), Sasao et al..

* Autoionization is used for fast Heo production in ground state.

Metastable He
-

have lifetimes ~10 mcs and ~350 mcs.

*We start looking for lifetime dependences of hyperfine states for
possible using this dependences for polarized 3He
-

production.

* This dependences are exist. And polarized 3He
-

production is
possible.

Polarized 3He
-

ions production


Fine and hyperfine structure of 3He
-

ions


Different hyperfine components of
metastable relative autoionization
3He
-

negative ions with different
orbital and spin projections have
different lifetime relative
autoionization.


Components with highest
momentum 5/3 have largest
lifetime ~350 μsec when
components with lower momentum
have lifetime ~10 μsec.

3He
-

ion beam composed only of
hyperfine components [5/2, +
-
5/2>
can be produced and then
quenching one of the hyperfine
levels by an RF resonant field can
be produced 3He
-

beam with
polarization ~100%.




(S. Manson, PR A,3, 1,147,1971)

The decay curve of 4He
-

measured at 10 K.

The solid curve is a fit to the data.
The insert shows a time region in
which the decay of the short lived J
=1/2 and J=3/2 levels dominate the
intensity. (P. Reinhed, et al.,PRL
103, 213002 (2009) )


Temperature dependence of the
measured lifetime of


the 1s2s2p 4Po5/2 level of 4He
-
. The
effect on the decay rate from
photodetachment by blackbody
radiation can readily be seen as a
decrease in the measured lifetime
above 100 K.


Separation of fine components of He
-

in the
magnetic field

Components with highest momentum
5/3 have largest lifetime ~350 μsec
when components with lower
momentum have lifetime ~10 μsec.

3He
-

ion beam composed only of
hyperfine components [5/2, +
-
5/2> can
be produced and then quenching one
of the hyperfine component by an RF
resonant field can be produced 3He
-

beam with ~100% polarization.

The fine
-
structure results are:



Δ
53
= 825.23 + 0.82 MHz,

Δ
51

= 8663 + 56 MHz.


Separation of fine components of 7 Li* in the
magnetic field

Energy as a function of
magnetic field for various
(1s2s2p) 4P substates of 7Li
The positions of the three
observed anticrossings are
indicated by A.

Production of polarized 7Li
through different lifetime of
metastable states is also
available.

(PHYSICAL REVIEW A VOLUME 3, NU MB E R
JANUARY 1971, Determination of Energies and
Lifetimes of the Metastable Auto
-
ionizing (1s2s2p)
4P States of 6Li and 7Li by a Zeeman
-
Quenching
Technique, M. Levitt and R. Novick, P. D.
Feldman).

He
-
/He+ yield and beam intensity vs. He+ energy in K target.



With 2 A He+ current
from BINP arc discharge
source it is possible to
have ~ 0.1 A of He
-

ions.
Up to 4 mA of 3He
-

with
high nuclear polarization
can be produced.


A. SZANTO DE TOLEDO and 0.
SALA,
Production of Negative Helium ions,
Revista Brasileira de Física, Vol. 7, Nº 1,
1977).

Polarized 3He
-

ion source


BINP High brightness arc discharge ion source with Cs jet
charge exchange target (as for BNL OPPIS)

A schematic of the experiment on He
-

beam production. 1
-

He+
source, 2


extraction system, 3


space charge compensation
Xe, 4


K (Rb, Cs) target, 5


bending magnet, 6


Decay
channel with solenoid and RF transition, 7
-
He+ beam; 8
-
space
charge compensated beam; 9
-
He
-

beam.

Polarized 3He
-

ion source


BINP High brightness arc discharge ion source with Cs jet
charge exchange target (as for BNL OPPIS)

A schematic of the polarized 3He
-

beam production. 1
-

He+ source, 2


extraction system, 3


space charge compensation Xe, 4


K (Rb, Cs) target, 5


bending magnet, 6


Decay channel
with solenoid and RF transition, 7
-
He+ beam; 8
-
space charge compensated beam; 9
-
He
-

beam;


10
-
Polarized 3He
-

beam; 11
-
neutrals of 3He beam.

3He
-

negative ion are separated from 3He neutrals by separating magnets (5). The separated
3He
-

beam (10) is accelerated for further use and can be converted to 3He++ by stripping in a
foil or He gas target. Beam tubes need be cooled below T~150K.


References have been found


It was suggested earlier that the differential

metastability of the (1s2s2p) 4P levels would provide

a possible mechanism for producing polarized electrons and nuclei,
especially those of 3He (I =1/2, ) and

6Li
(I=1).


P. Feldman and R. Novick, in Comptes Rendus du
Congres International de Physique Nucleaire, Paris,
1964, edited by P. Gugenberger (CNRS, Paris,
1964), Vol. II, 4a/C144, pp. 785
-
786.


Muons, Inc.

Polarized 6Li+++ Options

and other elements with low ionization potential

Existing Technology:


Create a beam of polarized atoms using ABS


Ionize atoms using surface ionization on an 1800 K
Tungsten (Rhenium) foil


singly charged ions of a few 10

s
of
µ
A


Accelerate to 5 keV and transport through a Cs cell to
produce negative ions. Results in a few hundred nA

s of
negative ions (can be increased significantly in pulsed
mode of operation)


Investigate alternate processes such as quasiresonant
charge exchange, EBIS ionizer proposal or ECR ionizer.
Should be possible to get 1 mA (?) fully stripped beam with
high polarization


Properties of 6Li: Bc= 8.2 mT, m/mN= 0.82205, I = 1


Bc = critical field m/mN= magnetic moment, I = Nuclear spin


Muons, Inc.



Production of highest polarization and reliable operation are
main goals ofthese ion sources development


Development of Universal Atomic Beam Polarized
Sources
(most promising, less expensive for
repeating) .


It is proposed to develop one universal H
-
/D
-
/He ion
source design which will synthesize the most
advanced developments in the field of polarized ion
sources to provide high current, high brightness,
ion beams with greater than 90% polarization, good
lifetime, high reliability, and good power efficiency.
The new source will be an advanced version of an
atomic beam polarized ion source (ABPIS) with
resonant charge exchange ionization by negative
ions, which are generated by surface
-
plasma
interactions.

Muons, Inc.

Realistic Extrapolation for Future

ABS/RX Source:



H
-

~
10 mA, 1.2
π
∙mm∙mrad (90%), Pz > 95%


D
-

~ 10 mA, 1.2
π
∙mm∙mrad (90%), Pzz > 95%

OPPIS:


H
-

~ 40 mA, 2.0
π
∙mm∙mrad (90%), Pz ~ 90%


H+ ~ 40 mA, 2.0
π
∙mm∙mrad (90%), Pz ~ 90%


OPPIS intensity can be higher, but


Polarization in
ABPIS/RX Source can be higher
because ionization of polarized atoms is very
selective and molecules do not decrease
polarization.

* 3He
-

~ 1 mA, Pz>90%


Muons, Inc.

Summary

Optimized versions of existing polarized
ion sources (ABPIS and OPPIS) and
advanced injection methods are
capable to delivery ion beam
parameters necessary for

Projected high luminosity of EIC.

ABPIS is preferable as universal source

It is possible to start development, design

and fabrication (cost ~1 M$).

Thank You for Your Attention.


Muons, Inc.