OPEN RESONATORS FOR AXION DETECTION

E U RO PE AN ORGANIZATION FOR N U CL EA R RES A E R C H

CERN/PS 69-40 June

ÍOP Î

1989

FERRIMAGNETIC RESONANCE, NAGNETOSTATIC NAVES AND OPEN RESONATORS FOR AXION DETECTION

F . Caspers and Y . S e me rt z i d is

ABSTRACT A ss uming

axion

predicts

coupling

m ag n et ic

field.

masses

m

to mi crowave For

the

micro-

wave

since

several years.

been

m e a s u r e d .In

detector, cavity than of

the open

as

to

confocal

r eceiver

improve

line width m materials.

resonance

is

a p pl i c a t i o n s

as

1-10 GHz

range.

velocity

of

variable The ir

cosmic

wav es

phase

a

a

very

signals

have

of this type of as

a

r e s o nating

and easier to take

tuning

a dvantage

(= Y t t r i u m - I r o n - G a r n e t ) occur

=

m

YIG -f l l ms

and t unable

filters

ferrite and

find

m

the

can be adj us t e d to mat ch the IQ“ 3 )

thus

the p r o c e e d i n g s

W or ks ho p on Cosmic A xi o ns B N L , April

photons, by

p er m i t t in g

c o n s t r u c t i o n of a directive d e t e c t o r .

P aper to be published m

strong

o p era ti on at BNL

related

sug ge s t e d

theory

a

w hi c h shows up w i t h a rather na rr o w

v e l o ci t y (beta

is m

bigger volume

delay lines

axions

followed

p ro posed

further

m a g n e t i ca ll y biased YIG M a g n et os t at i c

axion

of

of these

the se ns i v it ly

resona to r

c a v i t y . It is

fernmagnetic

d et e c t i o n

no clearly

to 10“b eV,

presence

reson a t or

it provides a c o n si de r ab le

a pillbox like the

cavity

narro wb a nd

Bo far,

order

in the

e x pe r i me nt al

c r y o g e n i c , tunable microwave sensitive

the order of 10"^

photons

13th and 14th 1989

of the

the

FERRI-MAGNETIC RESONANCE, NAGNET0STAT1C NAVES AND OPEN RESONATORS FOR AXION DETECTION F . C a s p e r s 11 The

Peceei-Quinn

strong

CP problem.

particle,

the

s ym me t r y 11

axion,

na me l y

e xp eriments light, mass

w h ic h m as s

could

T he re fo re

range

of

this

ma


10'6 e V ).

an open w i n d o w of 10"6 < eV < 10*

ex pe ri m e n t e r s

31 .

present




Properties

A

(AT ROOM

TEMPERATURE)

Yttrium-Iron-Garnet ( YI G)

“• V

K x/ * t (AT ROOM

TEMPERATURE)

inside

filters

a pp ar a t u s wou l d

the m i c r o w a v e

materials

be that of r ef er en ce

cavity at

the

end

of

* the

If

the axion mass m a t c he s

the electrons

radiate

This

of

excess

relevant coupling analysis

this f r e q u e n c y , then it is a b s o r b e d and

and excite

power

the T M 0 1 0 mode

e.g.

can be d e te c te d

is given by e q ua ti on s

Therefore,

an i m p ro v em e n t

power from axion

order

to g a m

same

order

F o ll ow i n g

the

the e xperiment

reso na to rs

where

reson at or s

are

frac ti on al coupling

the

DFSZ

the m ag ne t i c

to B 2 , that is we

This

the

a Q -value

inside

e le c t r o ns

c a v i t y . The m ag ne t ic

and

(the

feasible.

fie ld has

of the f e rr it e

as the cavity Q (~ 105 ), d iv id e d

is not on its F M R , the coupling is

c om pa r ab le

s i g n i fi c a n t v olume

a ss ur e d and

m

by the

e n ergy the

of,

to

case

exchange

same

s a y , more

the ferrite

the

to the ca vi t y is of

two

occurs

frequency.

magnetically

coupled

only if both

However,

for

a

than 10% filled with ferrite,

does not need to be on FMR.

of o pe ra t io n has been ap pl i ed at LANL for o r t h o g o n al l y

the RF B-field)

model.

field

by the ferrite material.

ro ug h ly at

cavity is

(and known)

o c cu pi ed

ferrite

str on gl y reduced.

below

the p r e ce s s io n fre q u en cy of

of m a g n i t u d e

fr a ct io na l vo lu m e

2.

(3).

the m os t w i th the use of the YIG spheres tune

to be rather h o m o g e n e o u s

mode

the

and

power

to the exact f r eq u e n c y of the m i c r o w a v e

If

f21

photon c o n v e r s i o n is p r o p or ti on a l

the c a v i t y , we should

the

cavity. The

of a factor of 10 m

a factor of100) w ou ld make In

the

of the R o c h e s t e r , B r o o k h a v e n , Fermilab group ^ } they conclude

that they are at a factor of ~ 3G0 m

gam

of

by standard HP techniques.

tuned a c c e le ra to r

c a vities

This

b i ased

around

60 MHz.

M A G N E T O S T A T I C W A VE S As

magne tostatic waves

are not known very wel l

m

general,

a short

i n t r o d uc t io n is g iv e n n o w . In p a r t i c u l a r , they open the p o ss i b i l i t y m at c h

the low p of cosmic

fields

m

axions

a c r y s t a l ; this mig ht

and also take a d v an t a g e

field,

H, w it h r es pe ct

terms

of

the

o r i e nt a ti o n s are:

principal

o r i e n t a ti on s

to the wave v e c t o r , k , m

unit

normal

of the

to

strong

provide a d i r e c ti o na l d e t e c t o r .

MS W p r o p a g a t i o n occurs for three In

(to

to

the

plane

of the bias

the plane of the s l a b . of

the

s l a b , n , the

(1) H0

x n = 0,

w hi c h gives

forward volume wave f2) H0 x n parallel wave

rise

iMSFVW)

to k , w h i ch gives

volume wave

to k, w h i c h gives rise to

isotropic

m

the

p r o p a ga t io n

d i st ri bu t e d across the ferrite

slab

by

by m u l t i m o d e

plane

the

in

actual

of

the

ferrite

application,

and energy that is

slab.

The

MSSW

energy co nfined p ri m a ri l y to one surface

d i s t r ib u t e d across the ferrite

p r o p a g a t io n

slab and a negative

The w a v e l e n g t h and delay per

is of

c e n t imeter

groupas

a

of f r eq ue nc y for r e p re s e nt a ti v e M S FV W and MSSW c o n f i g ur a ti o n s of p a rt ic u l ar

are pr esented m

:

Fig.

interest

for device

occurs;

orientation

magnetostatic

if

the

appli ca ti o n s)

at

S-band

3.

of the bias field H, d e t er m in e s the mode

p r o p ag a ti o n w h e n H x n is p ar a ll e l to wave

backward

p r o p a g at i on that is quasi-

[although

volume

magnetic

phase v e l o ci ty product. (the modes

m ag n e t o s t a ti c

s l a b . The M S B V W is c h a r a c te ri z ed by m u l t i - m od e

energy

f u n ction

the

is d om in a te d by the lowest order mode),

c h a r a c t er iz ed

3

surface

fMSBVW).

The M S F V W is c h a r a c t e r i ze d

Fig.

rise to the mag n e to st at i c

(MSSW)

(3) H 0 p arallel

with

to the q ua s i - i so t ro p i c m a gn e to st a t i c

cross

k,

produ ct

is

the

magnetostatic

zero,

f orward w ave p r o p a g a t g e s in the YIG

is plotted a gainst f r e q u e nc y

(from (8)).

of

surface

the q u a s i - i s o t r o p i c medium.

Wavelength

Note that MEW have v e l o c i ti e s 1 mm for 10 ps

of 3-300 km/s and w a v e l e n g t h

thick e pi t ax ia l

from 1 pm to

films.

P e rfo rm a n c e o f M a g n e to s ta tic W ave D evices P a ra m e te r

T ra n s d u c e r A rra y________ R efle ctive A rra y _______________ R e s o n a to r Fu ture

C u rre n t

Fu ture

1 -2 0

1-3 0

1 -2 0

1 -3 0

3 0 -8 0 0

10-1200

30-5000

10-1800

0 5

2

0 5

N.A 2

200 >1

50 4

N.A

N A

20

30