The (pseudo) Goldstone bosons arise naturally in many modern theories such as
supergravity, superstring theory and variants of general relativity with
torsion. By the other hand, there are well known indications that a large part
of the Universe mass exists in a form of dark matter. The most attractive model
of the dark matter is non-relativistic gas of the light elementary particles
weakly interacting with the "usual" matter \cite{b2} - \cite{b4}. We describe
ferromagnetic detectors, for search of arion(axion), where a high-sensitive
two-channel SHF receiver is used. Its sensitivity reaches to $10^{-20}\,Wt$,
with time of accumulation $1-10\,s$. Fourier analysis of signal provides a
survey in zone up to $\pm50\,KHz$ with spectral resolution $0.1 - 25\, Hz$.
There was applied a high sensitive SHF receiver based on a special computer
method of coherent accumulation of signals. It is possible to use the receiver
in other precise experiments: measuring of electron/positron beams polarization
in storage rings, investigation of parity violation, investigation of
atmosphere with radars etc.Comment: 6 pages, LaTeX, no figure

Boldyrev, A. P.

Kirpotin, A. N.

Rovkin, M. E.

Vorobyov, P. V.

English

arXiv

The (pseudo) Goldstone bosons arise naturally in many modern theories such as supergravity, superstring theory and variants of general relativity with torsion. By the other hand, there are well known indications that a large part of the Universe mass exists in a form of dark matter. The most attractive model of the dark matter is non-relativistic gas of the light elementary particles weakly interacting with the "usual" matter \cite{b2} - \cite{b4}. We describe ferromagnetic detectors, for search of arion(axion), where a high-sensitive two-channel SHF receiver is used. Its sensitivity reaches to 10^{-20}\,Wt, with time of accumulation 1-10\,s. Fourier analysis of signal provides a survey in zone up to \pm50\,KHz with spectral resolution 0.1 - 25\, Hz. There was applied a high sensitive SHF receiver based on a special computer method of coherent accumulation of signals. It is possible to use the receiver in other precise experiments: measuring of electron/positron beams polarization in storage rings, investigation of parity violation, investigation of atmosphere with radars etc

Vorobev, P V

Kirpotin, A N

Rovkin, M E

Boldyrev, A P

CERN Document Server

Po
st
Sc
rip
t〉  p
ro
ce
ss
ed
 b
y 
th
e 
SL
A
C/
D
ES
Y
 L
ib
ra
rie
s o
n 
21
 Ju
n 
19
95
.
H
EP
-P
H
-9
50
63
71
Ferromaghetic detectors of axions in RF (S X) band
P.V.Vorobyov, A.N.Kirpotin
Budker Institute of Nuclear Physics,
Novosibirsk, Russia
Internet: vorobyov@inp.nsk.su
M.E.Rovkin
Tomsk Academy of Automated Control Systems and Radioelectronics,
Tomsk, Russia
A.P.Boldyrev
Sakhalin RadioPhysical Place, S-Sakhalinsk, Russia
We describe ferromagnetic detectors, for search of arion(axion), where
a high-sensitive two-channel SHF receiver is used. Its sensitivity reaches to
10
 20
Wt, with time of accumulation 1   10 s.
Fourier analysis of signal provides a survey in zone up to 50KHz with
spectral resolution 0:1   25Hz.
There was applied a high sensitive SHF receiver based on a special computer
method of coherent accumulation of signals. It is possible to use the receiver in
other precise experiments: measuring of electron/positron beams polarization
in storage rings, investigation of parity violation, investigation of atmosphere
with radars etc.
1. Introduction.
The (pseudo) Goldstone bosons arise naturally in many modern theories such as super-
gravity, superstring theory and variants of general relativity with torsion. In the publica-
tions of last years the following (pseudo) Goldstone bosons are discussing: arion, axion,
familon, majoron etc (see review [1]).
The experiments on the search of such interactions are interesting from the point of
view of fundamental physics (new long-range force) and allow to obtain an information
about 10
6
  10
19
GeV -physics. It is clear that this energy domain is inaccessible for
accelerators.
By the other hand, there are well known indications that a large part of the Universe
mass exists in a form of dark matter. The most attractive model of the dark matter
is non-relativistic gas of light elementary particles weakly interacting with the "usual"
matter [2] - [4].
It means that a non-relativistic electron perceives the axionic condensate as a space-
inhomogeneous magnetic eld oscillating in time [3]. The eective strength of this eld is
equal to:
B
eff
= 2
p

a
v sin(m
a
t+m
a
vx+ ): (1)
Here 
a
is the density of the condensate,  = 
a
=
B
, 
B
is the Bohr magneton and  is
some phase.
The arion-electron interaction looks like the very weak dipole magnetic interaction
and may be characterized by the "arionic magneton":

a
= k
q
G
F
=8 (2)
or 
a
= 0:7  10
 5
k
B
. Here k
2
= G
a
=G
F
; G
F
is Fermi constant.
Let us suppose that v is equal to the "cosmological" velocity of the Earth: v 
10
 3
. Then the wavelength corresponding to the space variations of the eld B
eff
can be
estimated as
 = 0:1

1eV
m
a

(cm) (3)
If m
a
< 1eV the length   0:1cm and for samples of sizes  1mm one can treat the eld
B
eff
as a homogeneous one:
B
eff
= b sin(m
a
t+ ); b = 2
p

a
v; (4)
where  = 
a
=
b
. Such an exotic quasimagnetic eld with the amplitude about 10
 16
Gs
can be picked up already in the present state of the art. However, methods of its detection
depend essentially on the axion mass m
a
value being the frequency of the eld's B
eff
oscillations.
For massless arion [1] the equation of motion for the arion eld (a) and electron spinor
( ) are
a+
~
r( 
+
~ ) = 0;
i
@
@t
 =
h
 
r
2
2m
  q
ea
(~ 
~
ra)
i
 
(5)
The arion eld may be described as the eective magnetic eld
~
B
a
=  2
p

~
ra (6)
The behavior of arion eld in the wave zone has been considered in [1]. At large distances:
~
ra(~r; t) =  
~r
r
2

~n 
q
ea
8
Z

~
S(~r0; t0)d
3
~r0

; (7)
where ~n = ~r=r, t0   j~r   ~r0j. It is clear that in this case the arion wave the longitudi-
nal polarization:
~
4a k~n. Such "ario-dynamics" is the base for constructing arion/axion
detectors.
At present time there are used detectors based on coherent conversion axion(arion)!
photon in transverse magnetic eld [5] - [7]. For eective registration of axionic conden-
sate, it is advantageous to use a detector based on magnetized (anti)ferromagnetic. In this
case, axion-photon conversion happens not through triangle diagram with charged fermion
in loop, but thorough process, analogous Compton-eect on electron bound in atom. It
increases 
 2
times the probability of resonance conversion axion-photon ( = 1=137) [8].
So, as for search of cosmological axionic condensate, as for building of a laboratory
ferromagnetic detector based on conversionmagnon! axion! magnon, we need a high
sensitive SHF receiver permitting coherent accumulation of signal.
2. SHF ferromagnetic detector of axions.
If the quasimagnetic eld has frequency below 10
6
Hz (what corresponds to 0 < m
a
<
10
 8
eV ) it is natural to use a detector with a ferromagnetic rod as a sensitive body. Its
magnetization can be read o by SQUID. Detectors of such a kind have been used already
in search of arion and T-odd long-range forces [9] - [11]
In the range 10
8
Hz < m
a
< 10
10
Hz (m
a
< 10
 4
eV ) one can use the resonance axion-
magnon conversion in magnetic ordered media [8],[13]. Let us consider a resonator with
a working mode TE
110
and with a small spherical ferrous- or antiferromagnetic sample
placed in its center. An external magnetic eld is directed in such a way that the averaged
magnetization of the sample is perpendicular to the magnetic component of the resonator's
eigenmode. The magnetic resonance frequency is tted to be equal to the eigenfrequency
of the resonator. It provides a strong coupling between the magnetic moment oscillations
and the electromagnetic ones. If m
a
coincides with this frequency the spin waves will be
exited resonantly by the axionic wind. Electromagnetic oscillations coupled with such the
waves can be detected by a sensitive receiver.
Detailed discussion of the axion-magnon conversion and the corresponding computa-
tions can be found in papers [8], [12]. Here we present the result only. If P is a limiting
value of intensity which our receiver can detect, M is the sample magnetization, Q
f
is
the quality of the ferromagnetic resonance and H
0
is the external magnetic eld, then the
smallest detectable quasimagnetic eld is equal to:
b 
 
P
m
4
a
!
1=2
H
0
M
1
kLQ
f
(8)
and for P = 10
 15
erg=c, m
a
= 10
10
Hz, H
0
 M  10
3
Gs and (kL)
2
= 10
3
we obtain
b  10
 15
Gs. The use of the antiferromagnetic with a large Dzyaloshinsky eld (e.g.
FeBO
3
) as a sensitive body can give an additional factor  10
 3
in the right hand side
of (8) (see [8]).
2.1 A laboratory ferromagnetic detector
Let us consider a laboratory ferromagnetic detector for search of axions [8]. Its main idea
is following. A powerful SHF generator excites the resonance precession of electrons' spins
in ferromagnetic, lling a waveguide-resonator. Spin's coherent precession excites an axion
wave which spreads along waveguide axis and leaves it. The axion wave penetrates freely
through system of electromagnetic screens gets into receiving waveguide where it excites
the resonance precession of spin in ferromagnetic. The procession magnetic moment of
ferromagnetic produces an electromagnetic wave in the receiving waveguide-resonator;
High-sensitive coherent RF receiver registries this electromagnetic wave.
We see, there happens the double conversion in detector:
photon! magnon! axion! magnon! photon:
The work of ferromagnetic detector would be much more eective if we use a high
sensitive receiver providing a coherent accumulation of signal.
The usage of the coherent detection scheme with quadrature component registration
leads to the square root of N increase in the Signal-to-Noise (SNR) ratio as compared to
the non coherent scheme, where N is the number of accumulation cycles.
The general idea of the detector is following: The detector has a two-channel quadra-
ture superheterodyne receiver with a heterodyne, common for the both channels. As a
base generator, the heterodynes use a highly stable Rb frequency generator. The signal of
ferromagnetic resonance (induced with axion eld in the receiving waveguide-resonator)
feeds to the rst (high sensitive) receiver channel input, is heterodyning, splits into its
quadrature components and, after the matched lters, is registrating by couple of ADC's.
The "pilot-signal" of generator, through a "directed divider" and attenuator, feeds to the
second receiver channel input, and also heterodynes, splits into its quadrature components
and is digitizing by second couple of ADC's.
The overall synchronization is provided by the computer controlled generator of syn-
chronization pulses.
As the accumulation is completed, the data are read from the ADCs' buers into the
computer where some sucient processing takes place (a statistical analysis of data in
order to calculate zero levels and other hardware parameters; based on it, distinguishing
of pure quadrature components and compensation of their non-orthogonality; reducing to
the quadrature basis of the "pilot-signal" and the further Fourier analysis).
Such detector, with operating frequency is 9GHz, was constructed in BINP. There was
obtained following limit for the for electron-axion coupling constant: q
ae
< 10
 3
GeV
 1
or
B
eff
=B
0
< 10
 12
for distances less 5mm.
2.2 HALOSCOPE - detector of cosmological axion condensate.
Let us consider a detector of the cosmological axion condensate, HALOSCOPE [3]. It
consists of SHF resonator, working in mode TE
011
. In the center of resonator, in the bunch
of magnetic eld, there is placed a little spherical sample, made of (anti)ferromagnetic of
high ferromagnetic resonance quality. The resonator is placed into constant external mag-
netic eld so that the sample's magnetization is perpendicular to the magnetic component
of resonator SHF eld.
We select such magnitude of external magnetic eld that the frequency of ferromag-
netic resonance corresponds the own frequency of resonator at mode TE
011
.
Let the detector move through the axion condensate so that the vector of eective
quasimagnetic eld
~
b is perpendicular to the external eld. If the eld oscillation fre-
quency
~
b coincides with the the frequency of ferromagnetic resonance then a precession
of ferromagnetic magnetization vector will take place. There appears an oscillating com-
ponent of the sample's magnetic moment; it is well linked with the magnetic eld TE
011
of the resonator's oscillation.
This linkage provides a transmission of power from quasimagnetic wave to resonator's
electromagnetic eld (and back) which is possible to registry by a high sensitive RF
receiver.
There are possible two ways to use the receiver:
1) The signal of ferromagnetic resonance feeds to the high sensitive receiver input, and
is slitting into its quadrature components, relatively basis formed by very stable
heterodyne. In this case, we do not need the low sensitive support channel for
"pilot-signal".
2) A "pilot-signal" from very stable generator is using; it feeds to a support channel
input (low sensitive). This way looks more advantageous because:
- We can use SHF-modules of standard SHF receivers like "7-8", "7-11" and other
ones which contains SHF-amplier, heterodyne etc. A low stability of own rst
heterodyne does not matter because the coherentness is provided by high stable
"pilot-signal" which is easy to obtain.
- It is not necessary for the "pilot-signal" to be, simultaneously, very stable and
powerful enough.
- The "pilot-signal" may be used for adjusting of ferromagnetic resonance and for
calibration of detector (among measurement cycles).
This detector was constructed in BINP for operation in range 2 12GHz. We scanned
range 8   10GHz with sensitivity B
eff
< 10
 14
Gs. For this sensitivity level no axionic
signal was found. It is a preliminary result; we hope to perform a full scanning (2  
12GHz) with better sensitivity.
To increase sensitivity, we used in this work the method of coherent accumulation and
modulation of magnetized eld.
3. High-sensitive SHF receiver
We constructed a complex of tho-channel coherent receivers covering scope from 100MHz
to 12GHz [14].
The receivers are made by classic heterodyne scheme with double frequency transforma-
tion. To provide the coherence, a computer processing was used.
For each channel, the signal is heterodyned and split into its inphase and quadrature
components, which are digitized by couple of ADC's and, after accumulating cycle, are
read by computer.
A special very eective procedure performs a statistical analysis of accumulated sequences
and calculate oating zeros (of all tract of measure including ADCs) and parameters
of non-orthogonality of the quadrature splitter. After this procedure, there becomes
possible to obtain pure quadrature components of signals and to compensate their non-
orthogonality.
As the quadrature components are calculated, every couple of quadratures from accu-
mulating signal array is reduced to the quadrature basis of corresponding couple of "pilot
signal's" quadratures or, the same, random initial phases of "pilot signal" are subtracted
from the phases of accumulating signal.
So a coherent sequence of accumulating signal's quadratures is obtained; and its Fourier
analysis and other necessary processing are performing.
Using this method, there was reached the sensitivity  180 dB, while accumulating
sequence of length 4096.
Another complex was used in radar for investigation of atmosphere, with work fre-
quency of 150MHz. Its sensitivity is  190 dB [15].
This work was supported from by "COSMION" foundation.
References
[1] Anselm A.A., Uraltsev N.G. Physics of Fundamental Particles. | Proceedings of the
XX Winter School of LINP, Leningrad, 1985.
[2] Turner M.S. Phys.Rept., 197(1990), 67.
[3] Vorobyov P.V., Kakhidze A.I., Kolokolov I.V. Preprint IFUM - 460/FT, INFN,Milano
1994. (To be published in Yad. Fiz. No 6, 1995.)
[4] Sakharov A.S., Khlopov M.Yu. Yadern. Fizika, 57 (1994), 514
[5] Sikivie P. Phys.Rev., D32 (1983), 2988.
[6] Wuench W.U. et al. Phys.Rev., D40 (1989), 3135.
[7] Lazarus D.M. et al. Phys.Rev.Lett., 69 (1992), 2333.
[8] Vorobyov P.V., Kolokolov I.V., Fogel V.F. JETP Lett.,72(1989), 65,
Vorobyov P.V., Kolokolov I.V., Fogel V.F. Particle World, 1(1990), 163.
[9] Vorobyov P.V., Gitarts Ya.I. Phys.Lett. B208(1988), 146.
[10] Bobrakov V.F. et al. Pis'ma v ZhETF, 53(1991),283. (English translation see in Sov.
Phys. JETP-Lett.)
[11] Vorobyov P.V. Pis'ma Zh. Eksp. Teor. Fiz. 59 (1994) 486
[12] Barbieri R. et al. Phys.Lett. B226(1989), 357.
[13] Kakhidze A.I.,Kolokolov I.V. Sov.Phys.JETP, 72(1991), 598.
[14] Vorobyov P.V., Kirpotin A.N. et al. BINP 94-57, Novosibirsk 1994.
[15] Vorobyov P.V., Kirpotin A.N. et al. BINP 94-59, (To be published in "Radiotechnika
i Electronika", No 8   9, 1995.)


Ferromagnetic detectors of axions in RF (S - X) band

Ferromagnetic Detectors of Axions in RF (S - X) Band

Ferromagnetic Detectors of Axions in RF (S - X) Band

Abstract

Similar works

Full text

Available Versions

CERN Document Server