-
Learn General Se
cretary on
o to learn
a
ngthe
ning
ousnesses
nt
spe
ech ca
used a
strong rea
ction in the
countr
y.
ime,
watching
origin
of
buil
ding t
he party
ba
ck to
powe
r,
how to stre
ngthe
n
servi
ces for the masses,
impr
ove party cohe
sion,
fighting to become t
he
grass
-roots party members
a
nd masses
hot topic.
Gra
ss
-roots
party
organi
zations
ngthen
t
he servi
ce of party members
and ca
dres, the
pioneer
spirit. Di
stribution
of
grass-r
oots
party organizati
ons in all
walk
s of pe
ople,
clot
hing,
shelte
r, whi
ch
belongs to t
he
ner
ve endi
ngs of the
party organizati
on
a
nd
comments
re
putati
on has a
dire
ct per
cepti
on
of the masses.
Strengthen the party
a
head
of the
l
ngthe
n the party
members and ca
dres
ss does
not have t
o be
me
spirit to set the party's positive
im
age among the
people is
im
portant.
Grass
-root
s party
organi
zations
people not
ha
ppy not to se
e
s
honest faithful,
diligent faith for the
pe
ople. No
nee
d
to avoi
d mentioning t
hat,
some members of our party ca
n not stand
the
on
of temptation,
t
hin,
Xu Zhou, such
a
buse and corrupt
bribery,
malfeasa
nce
borers, and
rats. Two, is to
clean
up,
t
hin,
Xu, Z
hou's
soluti
on to rest
ore the
party's fresh a
nd natural,
solid a
nd
honest work
styl
e.
Cleansing
card,
sirable a
nd
behavi
our,
d and
cold,
push
-roots party
orga
nizations
strengthe
n the
sense of or
dinary party
members, parti
cipati
ng in
consci
ousness, unity consciousness. For
reasons k
now
n, members
of grass-r
oots
party branche
s less
m
obil
e, less
re
sources,
and
t
he constructi
on
of party organizati
ons have
some lag. Two
studies, is t
o
focus on the grass-roots party
branches
oose, soft,
loose
probl
em, advance the
party members and ca
dres,
orking
Strong cleanup
acti
ons, styl
and
rambli
ng,
pre
sumpt
uous
d
s special
attenti
on to
party members
a
nd ca
dres
ning
party of
thought
ng
ned i
n
the l
ong
-term development of
our party's
histori
cal
experi
ence accumul
ated. Two
i
s our party under the new
histori
cal conditions,
stre
ngthe
n the
party's constr
uction of a
ne
w
oots party
organizati
ons
shoul
d always
cat
ch the
hard
w
ork, results-oriente
d.
Two educational outcome
s are
long
-term orie
nted and
become a
n important impetus for the
w
ork.
d have
thre
e kinds
of
consci
ousne
ss
sic
lear
ning lie
s in the
doi
ng. Only the
Constituti
on address
t
he serie
s of party
rule
s, and do soli
d work,
be qualified
party members
ha
d a solid ideol
ogical
basis. Only the
ng
y, to form a
earn-do-do
ctive of
education. T
his requires that
t
he Organization
常用的氡测量方法
常用的氡测量方法
有电离室法、闪烁室法、双滤膜法、气球法、静电收集法、固体径迹法、
热释光法、活性炭被动吸附法和驻极体测氡法等。下面分别介绍这些方法的原理及优缺点。
2
.
1
电离室法
[1, 2 ]
含氡气体进入电离室后
,
氡及其子体
放出的
A
粒子使空气电离
,
电离室的中央电极积累
的正电荷使静电计的中央石英丝带电
,
在外电场的作用下
,
石英丝发生偏转
,
其偏转速度与
其上的电荷量成正比
,
也就是与氡浓度成正比
,
测出偏转速度就可知道氡的浓度。
本方法的优点是
:
方法可靠
,
直接快速
,
既可以直接收集空气样品进行测量
,
也可以使空
气不断流过测量装置进行连续测量
,
在实验室使用可较快地给出氡浓度及其动态变化。缺点
是
:
灵敏度低
(
探测下限为
10
—
40 Bq
?
m
3 [1,
2 ]
) ,
不适合低水平测量
,
设备笨重
,
不便现场使
用
;
测量时间较长
,
读数方法原始
,
要用肉眼观察指示丝的偏转速度。
2
.
2
闪烁室法
[3 ]
氡进入闪烁室后
,
氡及其子体衰变产
生的
A
粒子使闪烁室壁的
ZnS (A
g)
产生闪光
,
经
光电倍增管和电子学线路最后记录
下来。单位时间内的脉冲数与氡浓度成正比
,
从而可确定
氡浓度。
本方法的优点是
:
探测下限低
(
和闪烁室的几何形状等有关
,
一般可达
3. 7
Bq
?
m
3
,
设计
好的可达
0. 37
Bq
?
m
3
) ,
操作简便
,
准确度高
,
缺点是
:
测量时间较长
(3 h
以上
) ,
要求的设备
·
34
·
辐射防护通讯
1994
年
第
14
卷
第
6
期
较多
,
装置笨重
,
不便于现场使用。
沉积于室内壁的氡子体难于清除
,
使用时应经常用氮气或
老化空气清洗。保存时应充入氮气封闭以保持较低的本底
,
并经常刻度以保持测量的准确
性。另
外虽然可以用气袋或金属罐将现场气体取回实验室转移到闪烁室中测量
,
但气袋对氡
气的吸附和泄漏以及远距离情况下的运输问题还有待于研究。
2
.
3
双滤膜法
[4 ]
双滤膜筒的结构如图
1
所示。
抽气过程中
,
入口滤膜滤掉空气中已
有的氡子体
,
“纯氡”在通过双滤膜筒的过程中又生
成新的子体
(
主要是<
/p>
218
Po)
。其中的一部分为出口滤膜
所收集。测量出口滤膜上的
A
放射性活
度
,
根据氡子体的积累衰变规律即可求出待测空气中的氡浓度。
<
/p>
该方法的优点是它既可用来测子体浓度
(
进气口滤膜
) ,
也可测氡浓度
(<
/p>
出气口滤膜
) ,
其
探测下限低
(
约为
3. 7
Bq
?
m
3
) ,
方便快速。缺点是必须确保出口滤膜不被二滤膜之外的氡污
染
,
即必须防止衰变筒和滤膜漏气。本方法受相对湿度的影响较大
,
影响的程度对不同大小
earning e
ducation,
ne
ed thre
e kinds of
consci
ousness: one i
s to
esta
blish
an
integrate
d awarene
ss.
Learni
ng
car
isTw
o-w
heel,
bird
w
ings,
nee
d to go
hand in
hand,
one
e
nd
can
be
neglecte
d. Communi
st
the
oreticia
n and man.
Only
by cl
osely
combi
ning t
heory
a
nd
practi
ce
together in order to truly reali
ze
their val
ue.
ng
oundation is
not str
ong,
shaki
ng;
net to
net thousa
nds of accounts.
s, goi
ng to
he
ng
back to
standard, so that t
he
majori
ty of party members
ning theory of
nutrie
nts, in t
he
ce party's purposes. S
econd,
to esta
blish a se
nse
of dept
h.
ning
drawn,
entirely
dif
ferent, but
t
he orga
nic
unity
of the whole.
ning
e
ducation, we
need
t
o explor
e integrating
bit
do
ence
he
ng
simple room
instr
ucti
on,
onotone for
doing.
Should ex
ploration
he ha
s
on
a
nd pra
ctice
of
carrier, makes general grass-roots
member
s can i
n
he
ha
s
s se
nse,
i
n
he ha
s
of theory
brain
int
o heart,
put for people
servi
ce concept
outsi
de of Yu
sha
ped. T
hird,
t
o adhere to
l
ong
-term the
aware
ness. Style construction on the
r
oad forever,
catch the
long-term.
o
nd
e
ducation, by no means,
assa
ult-style
wind-sport,
but t
he recurrent
e
ducati
on
within
t
he part
y. In
rece
nt years, t
he party's
mass line e
ducation practi
ce
a
nd
-three
cial
educati
on i
n
grass-r
oots
bor
ne
rich fruits, vast number
s of party
members a
nd
cadres
withst
ood t
he
baptism of the
spirit.
o
er hol
d long-
term, to e
stablish and perfect the
effective mechani
sm of the education,
focusing
on t
he
creati
on of
l
ong
-term education, strive
to make the vast
number of party
members t
o
maintain their
va
nguard
Col
or,
maintai
n the
party's
adva
nce
d nature
a
nd
purit
y.
Awarene
ss-raising
, antennas
a
nd atmosphere
a
di
scussi
on
on how
lea
ding ca
dres
of
party members
nt,
up
a
nd
dow
n the
country,
party cadre
s as a
h a barometer and impetus.
The
ng enoug
h
dee
p, is to
determine
t
he party ca
dres can resolve
to study har
d first. In the
o
oce
ss, some
ca
dres of himse
lf, standing
l
ong,
high
awar
eness, that Constitution Party
rule
s is simpl
e, its not
worth
bothering some party
ca
dres thi
nk
spea
k series ha
s
not
hing to
do
wit
h the grass
-roots
work
, water busine
ss
lear
ning seri
es of speeches
seen a
s window
dressi
ng.
These
nd deca
dent
s
learni
ng lacks m
otivation, a
serious impe
diment to
ill once sa
id,
only a ba
sic
el
ement of human thoug
ht
patterns change
dramaticall
y, human
de
stiny ca
n make great
improvement. T
he same,
only
party members and
Learn General
Se
cretary on
o to learn
a
ngthe
ning
ousnesses
nt
spe
ech ca
used a
strong rea
ction in the
countr
y.
ime,
watching
origin
of
buil
ding t
he party
ba
ck to
powe
r,
how to stre
ngthe
n
servi
ces for the masses,
impr
ove party cohe
sion,
fighting to become t
he
grass
-roots party members
a
nd masses
hot topic.
Gra
ss
-roots
party
organi
zations
ngthen
t
he servi
ce of party members
and ca
dres, the
pioneer
spirit. Di
stribution
of
grass-r
oots party
organizati
ons in all walk
s
of pe
ople,
clot
hing,
shelte
r, whi
ch
belongs to t
he
ner
ve endi
ngs of the
party organizati
on
a
nd
comments
re
putati
on has a
dire
ct per
cepti
on
of the masses.
Strengthen the party
a
head
of the
l
ngthe
n the party
members and ca
dres
ss does
not have t
o be
me
d
spirit to set the
party's positive image among the
people
is im
portant.
Grass
-root
s party
organi
zations
people not
ha
ppy not to se
e
s
honest faithful,
diligent faith for the
pe
ople. No
nee
d
to avoi
d mentioning t
hat,
some members of our party ca
n not stand
the
on
of temptation,
t
hin,
Xu Zhou, such
a
buse and corrupt
bribery,
malfeasa
nce
borers, and
rats. Two, is to
clean
up,
t
hin,
Xu, Z
hou's
soluti
on to rest
ore the
party's fresh a
nd natural,
solid a
nd
honest work
styl
e.
Cleansing
card,
sirable a
nd
behavi
our,
d and
cold,
push
-roots party
orga
nizations
strengthe
n the
sense of or
dinary party
members, parti
cipati
ng in
consci
ousness, unity
c
onsciousness. For reasons
k
now
n, members
of
grass-r
oots
party
branche
s less
m
obil
e, less
re
sources,
and
t
he constructi
on
of party organizati
ons have
some lag. Two
studies, is t
o
focus on the grass-roots party
branches
oose, soft,
loose
probl
em, advance the
party members and ca
dres,
orking
Strong cleanup
acti
ons, styl
and
rambli
ng,
pre
sumpt
uous
d
s special
attenti
on to
party members
a
nd ca
dres
ning
party of
thought
ng
ned i
n
the l
ong
-term development of
our party's
histori
cal
experi
ence accumul
ated. Two
i
s our party under the new
histori
cal conditions,
stre
ngthe
n the
party's constr
uction of a
ne
w
oots party
organizati
ons
shoul
d always
cat
ch the
hard
w
ork, results-oriente
d.
Two educational outcome
s are
long
-term orie
nted and
become a
n important impetus for the
w
ork.
d have
thre
e kinds
of
consci
ousne
ss
sic
lear
ning lie
s in the
doi
ng. Only the
Constituti
on address
t
he serie
s of party
rule
s, and do soli
d work,
be qualified
party members
ha
d a solid ideol
ogical
basis. Only the
ng
y, to form a
earn-do-do
ctive of
education. T
his requires that
t
he
Organization
和形状的双滤膜筒有所不同
,
相对湿度越大
,
滤膜上测得的
A
放射性活度越大。解决的办法
是将双滤膜筒在不同相对湿度下刻度
,
求得相应的刻度系数。加大衰变筒体积可以提高灵敏
度
,
但衰变筒太大不便携带。此外该装置要使用电源
,
不便野外使用。
2
.
4
气球法
[5 ]
气球法是在双滤膜法原理的基础上发展起来的
,
所不同的是用气球代替了双滤膜筒
,
所
采用的气路和测量原理完全相同
,
它克服了双滤膜法不便携带的缺点。
本方法的优点是操作简单
,
方便快速
,
仅需
0. 5 h
即可给出氡浓度和子体潜能
,
其采样
体积不受限制
,
增加气球体积即可降
低探测限
(
例如
20 L
的气球和一定的测量程序
[6 ]
,
其灵
敏度为
37
Bq
·
m
- 3
)
。其缺点是气球的球壁效应
(
吸
附和泄漏
)
和相对湿度对结果的影响较
大。
为此使用时
,
要注意气球内外氡浓度不能差异太大
,
测量时间不能过长
,
对气球要在不同
相对湿度下进行标定
,
求出相应的湿度修正因子
[6
]
。
2
.
5
静电扩散法
[7 ]
该方法的原理是
:
由于球内外存在氡浓度差
,
外面的氡通过扩散经泡沫塑料进入球内
,
0. 25 h
左右建立平衡。泡沫的作用是阻挡氡子体的进
入。扩散到灵敏体积中的氡衰变产生
氡子体
,
主要是
218
Po
正离子
,
在电场作用下被收集在中央电极上
,
如图
2
可示
,
由
218
Po
再衰
变产生的
A
粒子被光电倍增管收集
,
经电子学线路整形
,
计数得到相应的脉冲数。通过相对
刻度就可以确定待测空气的氡浓度。
该方法的优点是探测限较低
,
为
1. 85
Bq
?
m
3
,
既可用于室内氡浓度的测量
,
也可连续监
测氡浓度的动态变化。缺点是设备笨重
,
不便于现场使用。中央电极的收集效率和相对湿度
有关
,
需分别标定。
2
.
6
固体径迹法
[8 ]
该方法的原理是
使空气自由扩散到装有固体径迹探测器的测量杯中
,
空气中的氡及衰
变子体产生的
A
粒子在径迹片上因
A
电离损伤留下径迹。在实验室中经简单的蚀刻处理
(
通
常是在
N aOH
或
KOH
溶液中
,
温度为
60
—
70
℃浸泡
3
—
4 h)
后
,
在光学显微镜下或用自动
火花计数器
作径迹计数。经刻度就可得到暴露期间的平均氡浓度。
其优点是
:
价格低廉、小型无源、径迹稳定
,
适于大规模的氡水平调查
,
能在
12
个月的期
间内进行累计平均浓度测量
。缺点是必要的测量周期较长
(
对目前可利用的探测器来说
p>
,
建
earning e
ducation,
ne
ed thre
e kinds of
consci
ousness: one i
s to
esta
blish
an
integrate
d awarene
ss.
Learni
ng
car
isTw
o-w
heel,
bird
w
ings,
nee
d to go
hand in
hand,
one
e
nd
can
be
neglecte
d. Communi
st
the
oreticia
n and man.
Only
by cl
osely
combi
ning t
heory
a
nd
practi
ce
together in order to truly reali
ze
their
val
ue.
ng
oundation is
not str
ong,
shaki
ng;
net to
net thousa
nds of accounts.
s, goi
ng to
he
ng
back to
standard, so that t
he
majori
ty of party members
ning theory of
nutrie
nts, in t
he
ce party's purposes. S
econd,
to esta
blish a se
nse
of dept
h.
ning
drawn,
entirely
different, but
t
he orga
nic
unity
of the whole.
ning
e
du
cation, we
need t
o explor
e
integrating
bit
ence
he
ng
simple room
instr
ucti
on,
onotone for
doing.
Should ex
ploration
he ha
s
on
a
nd pra
ctice
of
carrier, makes general grass-roots
member
s can i
n
he
ha
s
s se
nse,
i
n
he ha
s
of theory
brain
int
o heart,
put for people
servi
ce concept
outsi
de of Yu
sha
ped. T
hird,
t
o adhere to
l
ong
-term the
aware
ness. Style construction on the
r
oad forever,
catch the
long-term.
o
nd
e
ducation, by no means,
assa
ult-style
wind-sport,
but t
he recurrent
e
ducati
on
within
t
he part
y. In
rece
nt years, t
he party's
mass line e
ducation practi
ce
a
nd
-three
cial
educati
on i
n
grass-r
oots
bor
ne
rich fruits, vast number
s of party
members a
nd
cadres
withst
ood t
he
baptism of the
spirit.
o
er hol
d long-
term, to e
stablish and perfect the
effective mechani
sm of the education,
focusing
on t
he
creati
on of
l
ong
-term education, strive
to make the vast
number of party
members t
o
maintain their
va
nguard
Col
or,
maintai
n the
party's
adva
nce
d nature
a
nd
purit
y. Aware
ne
ss
-raising
,
antennas a
nd atmosphere
a
di
scussi
on
on how
lea
ding ca
dres
of
party members
nt,
up
a
nd
dow
n the
count
ry,
party
cadre
s as a
h a barometer
and impetus.
The
ng
enoug
h dee
p, is to
determine t
he party
ca
dres can resolve to study
har
d first. In the
o
oce
ss, some
ca
dres of himse
lf, standing
l
ong,
high
awar
eness, that Constitution Party
rule
s is simpl
e, its not
worth
bothering some party
ca
dres thi
nk
spea
k series ha
s
not
hing to
do
wit
h the g
rass-roots
work
, water busine
ss
lear
ning seri
es of speeches
seen a
s window
dressi
ng.
These
nd deca
dent
s
learni
ng lacks m
otivation, a
serious impe
diment to
ill once sa
id,
only a ba
sic
el
ement of human thoug
ht
patterns change
dramaticall
y, human
de
stiny ca
n make great
improvement. T
he same,
only
party members and
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