NGHI6NCCfU TRflOBOI NGHIEN CUV CHE TAO PHO KE GAMMA XACH TAY DUNG DE DO UEU VA NHAN DIEN DONG V| PHONG XA NGUYIN oufc TUAN V\Sn Khoa hoc va Ky thu i t H^t nhii Vign Nang lirang Nguyen W Viat Nam, 66 K[.]
Trang 1NGHI6NCCfU-TRflOBOI
NGHIEN CUV CHE TAO PHO KE GAMMA XACH TAY DUNG DE DO UEU VA NHAN DIEN DONG V| PHONG XA
N G U Y I N oufc TUAN
V\Sn Khoa hoc va Ky t h u i t H^t nhii Vign Nang lirang Nguyen W Viat Nam, 66 KH&CN
Pho ke gamma xach tay co cau tao g6'm mat kh6'i da'u do tIa gamma ntfi b§n ngoal vdl mpt kho'i xiif ly Da'u do nha'p nhay Nal(TI) co dp nhay cao diroc slii dung de do ph|n bd' nSng lifdng cua bi}c xa gamma, sud't lid'u moi trirdng xung quanh (theo phifdng phap chuy§'n pho thanh li§'u), tim va nh|n dl^n d£ng
vj phdng xa Ngoai ra, cdn cd d'ng dem Geiger-Muller difdc tfeh hdp trong khd'i xiif ly d§' do sud't lilu gamma d dai iid'u cao Khd'i xiil ly difa trdn vi xur ly bao gdm cac mach di$n tilf xiif ly xung, phan tich da kdnh, lifu trif dif iidu, hien thj LCD, ban phim, giao tid'p theo ehud'n ethernet va pin sac Li-ion Ph^ k§' gamma xach tay cd the suf dung difdc d trong phdng thi nghiem cung nhu trong dieu kidn hidn trifdng Chdc ndng chinh cua thid't bj ndi chung la nhdn didn dd'ng vj phdng xa ma khong can phai ke't nd'i vdi may PC Nhiing chdc nang khac cua thie't bj la dd tim ngudn phdng xa va do sud't lidu Phd' kd' nay rd't phu hop cho cac dng dung nhu kie'm soat phdng xa moi trifdng, kiem soat chd't thai phdng xa, kl^m soat vi|c budn ban bat hdp phap cac ngud'n va vdt lidu phdng xa, k i l m seat phdng xa trong phd'lidu kim loai; trong cdng nghidp hat nhdn, y hgc hat nhan va i7ng phd sir cd'bdc xa
TH khoa: pho ke gamma
Mfftfau
DESIGN AND CONSTDUCTION OF THE PORTABLE GAMMA- „ ^ „ , ^ „ , ,„ ,,„ ,
Pho ke gamma xach tay la DAY 6PECTP0METED FOD ENViDONMENTAL D 0 6 E DATE mdt cdng eg can thilt dung d l MEA6UDEMENT AND DADI0I60T0PE IDENTIFICATION "^gn dien d^ong vj phdng xa
trong viec kiem tra an ninh, an todn bflc xg, khao sat mdi trfldng cung nhu cae flng dyng khac trong khoa hpc va cdng nghi§p Thilt bj thu ttigp va phan tich dO' lieu dat dUdc tfl dau dd phdng
xg phu hdp Nhflng skn ph^m
thfldng mai hien ed cua pho ke gamma cdn bao gom nhilu chflc nang can thiet khac nen cd gia
thdnh cao va khd duy tri bko
dudng Do dd, viec thilt k l chi tao mdt pho ke vdi kich thfldc thu gpn d l cd the hoat dpng nhU mdt he thd'ng dpc lap trong dieu kien hien trudng ddp flng yeu cau flng dyng gpn nhe dupc dSt
ra Cac ky thuat hidn dgi v l vi mgch to hpp tfldng tfl, bien doi tfldng tfl - Sd chat Ifldng cao va vi xfl ly da dfldc ap dung trong vi$c nghidn cflu phat triln thilt bi
Summary
The portable gamma ray spectrometer is composed of an external gamma
radiation detection unit and a processing unit Highly-sensible Nal(TI)
scintillation detector is used for measurement of gamma radiation energy
distribution, ambient gamma radiation dose rate equivalent (spectrum-dose
conversion method), search and Identification of radionuclides
Geiger-Muller counter tube is integrated into the processing unit for measuring higti
gamma dose rate The microprocessor-liased processing unit comprises
of pulse processing electronics, multi-cbannel analyzer, data storage,
LCD display, keypads, ethernet interface, and Li-ion rechargeable battery
Portable multifunction scintillation gamma spectrometers can be used in
laboratories as well as for working in field conditions It's main spectrometer
function is radionuclide identification without connection to a PC Additional
functionalities are search and detection of radioactivity sources and dose rate
measurement This spectrometer is Ideally suited for radioactive environment
monitoring, radioactive waste monitoring, illicit trafficking monitoring of
radioactive source and materials, radiation monitoring of metal scrap; nuclear
industry, nuclear medicine and emergency
Keywords: gamma spectrometer
^" CdNCNCHEVIETNiSf ^ ° ' ' " ^ ' " ' ° ^ ^
Trang 2Thiet ke che tao
Dong vj phdng xg trong qua trinh phan ra phat
ra tia gamma vdi nang Ifldng dac trflng Cac kieu
dau dd bflc xa gamma nhfl logi tinh t h i nhap nhay
Sodium Iodide (Nai), hay tinh the ban ddn nhu
Cadmium - Zinc - Telluride (CdZnTe) hoac High
Purity Germanium (HPGe) d i u cd the ghi nhan
nang IUdng cua tia gamma Trong cdc dau dd nay,
bflc xg gamma tao ra eae xung anh sang hoae dien
tich ty Id vdi ddng nang cfla bflc xa Cac khdi dien
tfl hgt nhan bao gdm tiln khuech dgi, khulch dgi,
bien dli tfldng tfl - sd (ADC) va phan tich da kenh
(MCA) se hinh thanh viec khuech dgi va tao dang
tin hieu tfl d i u dd, chuyin doi tUdng tU sang sd va
phan chia cac xung d i n theo bien dp ty le vdi nang
lupng Sfl phan bd dat dflpc gifla so d i m xung theo
nang Iflpng chinh la pho gamma
Yeu cau thilt k l cd bcin ddi vdi pho ke xach tay
phai dgt dupc la mflc tieu thu cdng suat tha'p Thilt bj
phai cd cau trflc nhd gpn de cho phep sfl dung trong
khoang thdi gian mpt ngay ch? vdi mdt bd ngudn
pin nhd D l dat dfldc dilu ndy, cac linh kidn dien
tfl cdng sua't tha'p dflpc chpn Ifla cho viec sfl dung
trong khoi MCA va cac thiet k l maeh dien tfl dfldc
tinh nang ci!ia bd MCA danh cho nhflng flng dung
hien trudng Thiet ke cung sfl dung nhflng mach tieh
dang sfla chfla, nang cap khi can thilt
Sd do khdi cua thie't bi dflpc eh! ra d hinh 1, gom
cac khd'i dien tfl chflc ndng nhfl sau:
Hinh 1: sd dS khdi cua phS k§ gamma xich tay
Nai Scintillation Detection Unit (1): to hpp dau dd
nhap nhay Nai cd kich thfldc 2,48 x 2,48 inches bao gom cdc thanh phan cd ban nhfl "tinh the nhap nhay Nal(Tl) - dng nhan quang dien PMT" va cac mgch tiln khulch dai, khulch dgi hinh thanh xung ehuin Id'i ra de cd t h i dfla thang den Id'i vdo cija bd phan
tich da kenh MCA, ngudn nudi cao ap cho dau dd vk
bu trfl anh hfldng eua nhiet dp
-I-500V High Voltage (2): khd'i ngudn nudi cao ap cho
dau do Geiger-Muller
Internal GM Detector (3): dau dd Geiger-Muller tich
hdp de do dai lieu cao
GM Pulse Shapper (4): khd'i hinh thanh xung cho
dau dd Geiger-Muller
Sample & Hold (5): khoi lay mau va gifl dinh xung /VD converter (6):kh6\ chuyen doi tfldng tfl - sd Embeded Microprocessor (7): vi xfl ly thflc hien logic dieu khien vk thu thap dfl lidu; chuyin doi ky thuat so
tfl phd' sang lieu; bd nhd IUu trfl ham chuyin doi G(E)
va cac chflc nang khac
Real Time Clock module (8): khd'i thdi gian thuc Graphic LCD Display (9): khoi hien thj graphic LCD Functional Keypad (10): khd'i ban phim chflc nang GPS module (11): khdi thu nhan tin hieu GPS EEPROM storage (12): khd'i bd nhd Iflu trO pho RS-232, Ethernet Interface (13): khoi giao tilp theo
chuan RS-232 va Ethernet
Li-ion Battery Power Supply (14): khoi nguon nuoi
bang pin Li-ion
DC Converter (15): khoi chuyen doi nguon
DC-DC
6 trang thai hoat ddng, xung den tfl khdi dau do dfldc dfla den khoi lay mlu vd gifl dlnh xung Mdi xung dfldc dfldc lay mau va bie'n doi trong mpt chu trinh ADC mat 1,5 i^s va sau dd tgo ra ngdt dfla din
vi xfl ly de khdi tao chflc nang IUu trfl dfl lieu, Nhung xung de'n tiep theo se dUdc xfl ly khi chu trinh IUu trfl vao bp nhd hoan thanh Cac module ehfldng trinh chflc nang cija vi xfl ly dflpc vilt bang ngdn ngfl C51 cho viec thu nhgn pho va thflc hien cac phep tinh Ngoai ra, mpt cdng cy phan mem dflpc phat triln dfla tren Labview de hd trp pho k l khi giao tiep vdi may PC
Phan tich pho va nhan dien dong vi phdng xa
Chuan nang lut/ng Ckc ham sd hieu chuan mac djnh (kenh theo
nang Ifldng va do phan giai nfla chilu cao theo
Top cM KHOA HO J
Trang 3NGHISN CLfu - TRFIO DOI
nang IUdng) ducfc xac dmh bang each khdp ham
giOa cac dinh pho gamma doi vdi ham Gauss
Phep hieu chuan nay dUdc thUc hien vdi cac nguon
chuan; •'»»Cd(89 keV), "Co(122 keV), "'Bă356
keV), "'Cs(662 keV), »'Nă1274 keV) va "00(1173
keVva 1332 keV)
Viec hieu chuan nham xac dmh cac he so hi§u
chuan a,, a,, a,, b,, b,, b, va c,, c^, c, cho cac ham
hieu chuan sau:
chn = a, + ậE + aj.É Kenh theo nang
luijng (E CO don vi la keV)
E = b, + bj.chn + bj.chn' Nang IUdng theo
kenh {E c6 đn vi la keV)
FWHM = c,+ c,.E + C3.E2 Dp phan giai nOa
chieu cao theo nang luong (E va FWHM cd đn vi
la keV)
Thu vien dong v| phdng xa trong phan mem cCia
thiet bl cd the bao gom 8 dong vi phdng xa cd ban
nhu bang 1
Dong vj
Cd-109
Co-57
U-235
1-131
Cs-137
Mn-54
Co-60
Na-22
NangIUdng (keV)
88
122
185
364
662
835
1173
1274
Cac ham só hieu chuan nay dudc tich hdp trong
phan mem cua thiet bi nhu la phep hieu chuan mac
dinh Khi thiet bj hoat dong, phan mem si!f dung cac
ham nay de xac dinh vi tri cua dmh phd gammạ
Ngudi sCf dung cd the dung nguon ^^^Cs(662
keV) de kiem tra phep hieu chuan mac djnh Neu vi
tri dinh 662 keV khong trung vdi kenh nhu da dUdc
tinh toan trong phep hieu chuan mac djnh thi phan
mem se thay đi cac he só khuech dai a va b^ de
bu trU vao su thay đi dọ Phep hieu chuan mdi nay
se trd thanh phep hieu chuan mac dinh
Tim dinh tudgng va nhan di$n dong vj
Thu vien ve dong vi phdng xa cua thiét bi cd chCfa
sSn 8 dong vj Mdi khi thu vien hay phep hieu chuan
nang IUdng bi thay đi, thiét bj se tu tinh iai vj tri
kenh cua dinh P^ va do rong dinh (FWHM) cho mdi
logi đng V! trdng thu vien theo cac ham sau:
P^ = a, + a,.E + aj.Ê va FWHM = c, + c^.E + c,.e
Trong do, E la nang IUdng tUdng Ung vdi dinh gamma cua dong vj va a,, â, ajla cacjie sd hieu chuan dUdc IUu glO trong thiet bj Khi thi^t bj 6 trong che dp thu nhan, no se tim toan bp cac dinh co trong thu vien trong khoJng thdi gian 6 giSy rnpt lan Thij tuc chi tiet cho viec tim dinh đi vdi mdi đng
vj dUdc cu the hda theo cac budc dudi dfiỵ Hinh 2 the hien mpt dinh phd co kenh la P„, sd d^m C^, cac
vi tri kenh trai ROI, va phai ROI, cua vung quan tam ROỊ
Hinh 2: vung quan tam ROI
Budc 1 Lam trdn dO lieu thd cija phd thu nhan
theo 5 diem iien tiép nhau:
Smodth[ii] = (-3.raw[ii-2] + 12.raw[ii-1 ] + 17.raw[iil + 12.raw[ii+1] - 3.raw[ii+2])/35
Trong đ, raw[ii] la sd dem tai kenh iị
Budc 2 Til gia tri kenh cua dinh P„ tinh dudc theo
nang IUdng d cong thdc tren, tim kenh cija dinh C,,, bang each tim kenh cd sd dem cue d?i trong dO iieu
da dUdc iam trdn trong dai (P,, ± 0,5.FWHM)
Bade 3 Thiet lap cac vi trf kenh toan cue cua
vung quan tam ROI theo vi tri k§nh eua dlnh C, tim thay d tren theo eac cong thUc sau:
L^ = P,_- 1,5.FWHM va R^ = P„ + 1,5.FWHM
BMc 4 Thiét I4p cac vi tri kenh trai ROI|Va phSi
ROUhuc sU cho vung quan tam ROI:
- Gia trj kenh trai ROi, dUde xac djnh bang viSc tim gia tri nho nhát trong dO lieu lam trdn trong dSi
to kenh L^ den kenh (P„ - 0,5.FWHM)
- Gia trj kenh phai ROI, dUdc xae djnh bang viSc tim gia trj nho nhát trong dO liSu lam trdn trong dJi
Trang 4tu kenh (P,, + 0,5.FWHM) den kenh R,^
Budc 5 Tinh ctfa sd dd rong kenh cua vung quan
tSm ROI: W = ROI,-ROi,+1
Budc 6 Thiet lap gia tr; m theo P,^, m la sd kenh
dupc si^ dung de tinh gia trj trung binh eua phdng
trong khoang ROi
Ne'uO<P„< 180, m = 1; 1 8 0 < P „ < 3 8 0 , m = 3;
380 < P„ < 640, m = 5; trudng hdp khac m = 7
Budc 7 Tinh dd dd'c (Slope) CLia dudng phdng:
Slope =
ROI, - ROI,
2J.BKG .fl^"'
2m Budc 11 Tinh sd d i m thflc sfl tai moi vj tri kenh
trong vung cfla so ROI:
net[ii] = raw[ii] - (slope.(ii - ROI,) -f N,)
neu net[li] < 0 thi dat net[ii] = 0
Budc 12 Tinh m^ng dfl lieu Gauss trong vflng
cfla so:
Gpi] = exp[ - (\\-Pf/6% trong dd 8 = FWHM/2,355
Bade 13 Tinh gia tn 6 - he sd tfldng quan
(correlation coefficient) gifla gia trj cua dinh pho do
dflpc (NET) vdi gia trj ly thuyet theo ham Gauss (G)
tgi vj trf dfnh nhan biet
Toan bd cac phep tinh tong sd dim dupc tinh tfl kenh ROI, den kenh ROI^
, {NET.Gf
Trong do N^ la sd dem trung binh tai kdnh ROI^
va N| la sd dem trung binh tai kenh ROI, dupc tinh
nhu sau
{N\chn^ - 3]-H N\chn, - 2]+ NJchn, -1])
' " 3
{N^chn^ + l]-H N^hn^ + 2]+ N\chn^ + 3])
3
Bildc 8 Tinh gia trj phdng (BKG) trong vung cfla
so ROI da xac djnh theo nguyen tac tinh dien tich
hinh thang:
BKG = (N^+ N,).W/2
Bade 9 Tinh td'ng sd d i m thUe sU (NET_SUM)
trong vung cfla so bang each la'y td'ng sd dem dfl
lieu thd tfl vj tri kenh ROI, d i n vj tri kenh ROI, va trfl
di gia trj phdng:
NET.SUM = ^ r a w [ / / ] - BKG
Bade 10 Tinh hd sd t^ Id D gifla sd d i m thflc sfl
va phdng:
NET SUM''
\NET\'\G[
Trong dd: NET.G = ^nei[ii]G[ii'\ vk bien dp:
Bade 14 Neu thda man cac dieu kien sau ddy:
hd sd tfldng quan du Idn, tflc la 6 > 0,5; ty sd gifla sd dim thflc va phdng D > 1; tong sd d i m thflc NET_ SUM > 20 thi xem nhfl dong vj da dflpc nhan biet Cac budc tim dinh tfl ddng vd nhan dien dong vj phdng xa theo thfl vien cd san neu tren se dfldc cu the hda thanh thuat toan va dflpc trien khai thflc thi trong module phan mem cho CPU cua thiet bj
Do suat lieu moi iruiHig
Tong quan ve phwang phkp JAERI
Phfldng phap JAERI dfldc phat triln bdi Monuchi
vd Miyanaga nam 1966 [1] Thij tyc chuyen doi tfl pho bien dd sang td'c dp phPi nhilm dflpc bieu diln bang phfldng trinh (1) dudi day [1 ] Ddng dau tien la Viet tat cua cac khai mem cd ban cua phUdng phdp JAERI, trong khi ddng thfl hai the hien cac thu tyc tinh toan cu the khi thflc hien phfldng phap dflpc ap dung cho mdt phd' bien dp thu nhan dfldc tfl bd phdn tich da kenh
x=[-y{E)G(,B)
= X;-'-'W(/)G(/)
Trong dd: X = Sua't lieu chieu (2,58.10'° Ckg ' h ' hoac uR.h'); N(E) = Phd bien dd theo nang luong (tdc dp dem cpm theo keV): N(i) = Phd bien dp theo kenh (tdc dp dem cpm theo kenh); E = Nang IUdng (keV), i = Sd kenh; E^„ = MUc nang IUdng phan biet dUdc (keV); E„„^ = Nang IUdng tdi da de danh gia sua't iieu (keV)';"l„,„ = Sd kenh tUdng Ung £„,„; 1„„
= Sd kenh tUdng Ung vdi E„,„; G(E), G(l) = Toan tCl bie'n ddl phd - iieu (2,58.10'» C k g ' tren cpm) cho nang lupng E hoac kenh I
PhUdng trinh 1 cho ta xac dmh dupc lieu chidu
do tia gamma trong dai nang lupng tU 0 den 3 MeV PhUdng phap nay cd the ap dung chd bat ky dSu dd nad tao ra phd nang lupng tUdng Ung Ddi vdi trudng hdp dau dp nhS'p nhay Nal(TI), hinh dang va kich thudc eua tinh the la nhan td chlnh cho vi#c x4c dmh
Tapch KHOSHOC
Trang 5ham dap flng G(E) Ham G(E) cho cac loai dau do
nhap nhay Nal cd kich thudc khac nhau dUdc chi ra
Nal(TI) da tinh dUdc, nd cd the ap dung cho bd't ky
dau dd Nal(Tl) cd cung kilu
Hinh 3- ham G(E) ciia cic dau do nha'p nhay Nal(T1)
CO kich thudc khac nhau
PhUdng phap hdm G(E) la mdt phfldng phdp noi
tieng cho viec chuyen doi sang lieu tfl mdt pho bien dp
do dflpc Su phu hpp cua flng dung dUa tren viec danh
thu tyc chuyen doi pho mdt each ddn gian
Gia trj sua't lilu cd the dgt dflpc bang cdch nhan
sd d i m tren kenh vdi gia trj ham G(E) tfldng flng vdi
mflc nang Iflpng cua mdi kenh va cpng don ta't ca
thflc hien dfldc bdi thu tuc ddn gian neu tren
Thu tiJc tinh toan cy the xac djnh ham G(E)
Kich thfldc cua cac dau dd nhap nhay da dfldc
khdo sat bao gom 1" x 1", 2" x 2", 3" x 3", 4" x 4",
5" X 4" ddi vdi logi hinh try va 2"<p, 3"(p, 5"<p dd'i vdi
logi hinh cau [2] Cac cau hinh chilu xa bao gom:
4 loai kerma, 4 logi lilu tfldng dfldng 6 dp sau 1 cm
va tflPng dfldng lieu hieu dung vdi 5 cau hinh hinh
hpc khac nhau [2] Dai nang Ifldng cua tia gamma
la tfl 50 keV de'n 10 MeV Ham dap flng cua dau dd
trinh MARTHA [2]
Hdm G(E) cd the dfldc xac djnh thdng qua
phfldng trinh da thflc xap xi (2) sau [2]:
cac he sd A(K) eua phfldng trinh da thflc xap xl ddl vdl ham G(E) flng vdi dgi Ifldng lilu tfldng dfldng
d cau hinh chieu theo mat phang song song (dose equivalent in plane parallel irradiation) (H*(10)) dfldc chf ra 6 bang 2 [2] (JAERI-M, 91 -204)
D l xac djnh gia tn ham G(E) cu the cho cho diu
dd sfl dung cd kieh tiifldc 63 x 63 mm (tfldng dfldng vdi 2,48" X 2,48"), chung tdi dung phfldng phdp ndi suy tren cd sd cac so' lieu da cd cua ham G(E) da
dfldc tinh cho eac dau dd cd kich thfldc 1", 2", 3",
4", 5" de tao ra cac gia trj can thiet eho dau dd cfla minh Cdc budc t i l n hanh nhfl sau:
BiJdc 1 Tinh cac gia trj ndi suy cho dau dd cd
kich thudc 2,48" sfl dung cac gid trj k i t qua cfla ham G(E) (theo b^ng ke't qua tinh cua phfldng phap JAERI) cija cac dau do cd kieh thfldc 1", 2" 3", 4", 5" tai cdc mflc nang Ifldng 50, 60, 80, 100, 130,
165, 200, 300, 400, 500, 600, 800, 1.000, 1.290, 1.500, 2.000, 2.500, 3.000, 4.000, 6.000, 8.000, 10.000 keV
BiJdc 2 Sii dung eae gia tri ndi suy ti'nh dfldc tfl
bfldc 1 vd edng cy phan m I m Originl.ab Pro, phan ti'ch cac dO lieu thflc nghiem ndi suy va tgo ham khdp da thflc mdi theo phfldng phap binh phUdng tdi thieu cho dau dd 2,48", ehinh la ham G(E) Kit qua bieu didn do thi ham G(E) d hinh 4 vd 5, bang
1 la bie'u thflc cua ham G(E) vdi he sd tUdng quan dat 0,99999
Bing 1
Trong dd: Kmax = Sd bae cua da thflc; A{K) =
He sd se dflpc xac dinh theo K; E = Nang Ifldng vdi
ddn vj la keV; M = Sd nguyen se dflde xac djnh theo
loai detector
PhUang trinh da
thQc cCia ham G(E) Hdm
G{E) = BO + B l E + B 2 E ' + B3,E» + B4.E' + B5,E^ + B6.E= + B 7 E ' + B8.E»
H 8 s 6
BO B1 B2 B4 B6 B8
G\& tn
1510,6659 -4405.049 5546,4069 -3944,231 1731,5689 -480,3098 82.19757 -7.93659
0.33118
Sal s6 ctiu^n
96,42088 294.10606 387.56292 132,33566 38,42331 6.89158 0.69836
c TapchiKHOAHQC ^
Trang 6NGHIEN cufu-TRRO SOI
Dua vao harn G(E) mdi nay, ta cd the tinh ra
cac gia trj eu the c i a ham t?i eac mUc nang lupng
tuong Ung vdi gia tri kenh ghi nhan dudc tO bd ptian
tich da k6nh MCA, tU do cd the tinh ra dupc gia tri
sua't lieu sau cung mong mudn PhUdng phap npi
suy nay cd the ap dgng de tinh cac gia tri ciJa ham
G(E) che cac dau dd cd kich thudc bat ky trong dai
t i l l "-5"
Kel qua
Tay xach Man hinh graphic LCD
Hinh 6: ph6 lie gamma xach tay
Phd ke gamma xach tay da dupc thie't ke che tao
hoan chinh nhu hinh 6 vdi cac dac trung ky thuat
sau;
- Dau dd nha'p nhay Nai: 2,48" x 2,48", dJi nang
lupng: 50 keV-3 MeV, dd phan giai nang lupng:
6,3% tai 662 keV ('"Cs), do nhay: 1.960 eps/uSv/h
("'Cs)
- Dau dd Geiger-Mueller (tieh hdp ben trong thiet
bj): dng dem chUa khi loai Ne + Halogen, dd nhay
Gamma (««Co): 0,26 cps/mR/h
- Phan ti'ch bien dp da kenh: do phan giai 2.048
kenh, dung lupng: 4 liytes/kenh
• Man hinh hien thi Graphic LCD: 128 x 64
pixels
- KhS nang IUu trQ: 8 phd, cd the md rpng
- Dk do suat iieu (DOSE RATE EQUIVALENT
H*(10)):
DSu dd nha'p nhay Nai: 0,01 nSv/h-80 nSv/h
Dau dd Gelger-Mueller: 10 nSv/h-100 mSv/h
- D4i dd iieu tich luy (TOTAL DOSE EQUIVALENT
H'(10)): 100 nSv-1 Sv
> - KhS nang nhan dien ddng vi phdng xa: '''Co,
" ' I , '"Cs, " M n , " C o , "Na, "^^Eu
- Giao tie'p may tinh: thdng qua cdng Ethernet
^ - Dai nhiet dp hoat dpng: tU 0»C de'n tSO'C, dp
am hoat dpng tU 30% de'n 95%
- Ngudn nudi: pin sac Li-ion vdi thdi gian hoal dpng lien tuc 12 gjd
- Kich thudc: 2" x 4" x 8" (may do), 6 88x315 mm (dau dd)
- Tdng trpng iupng (may do + dau dd): 5 kg Ket qua do dac hieu chuan vdi dau dd nha'p nhay Nai cua phd ke gamma xach tay dUa theo ham chuyen ddi phd sang iieu G(E) neu tren dUdc chi ra
d bang 2 vdi sai sdnhd hon 10%
Bang 2
Sui't
l i l u chuan (liSv/h)
0,68 0,77 2,7 3,06
10
15
20
25
30
35
40
50
Lan
(^Sv/h)
0,77 0,8 2,61 2,97 10,08
15 20,12 25,46 30,59 35,04 41,69 46,72 52,77
Lan
do 2 (^Sv/h)
0,72
0,85
3,03 10,27 15,01
20,36
31,11 35,42 39,71
45,53
Lan
d o a (^Sv/h)
0,8
0,87 2,69 3,09 10,17 15,1
19,79 24,92 29.55
39.86 45,97 52,9
Gia trj trung binh (MSV/H)
0,76 0.84 2,65 3,03 10,17 15.04 20,09 25,02 30.42 35,04 40,42 46,07 53.13
Gia tr[
TB trir phong (jiSv/h)
0.66 0,74 2,55
10,07 14.94 19,99 24.92 30,32 34,94 40,32 45,97 53,03
Sai
s o {%)
2,5 3,9 5,6 4,2
0,4 0,1 0,3
1,1 0,2 0,8 2.2 6.1
Ket luan
Pho ke gamma xach tay da dUdc thiet l<e che
t^o hoan chinh Ket qua cua viec nghien ciiu phat
tnen da tao nen mot thiet bj vdi nhQng tinh nang dgt dadc theo yeu cau de ra cung vdi gia thanh thap,
(<ich thudc nho gon va sii dung than thien Cac dSc
trung cua thiet bi dap Ung dUdc doi h6i cho nhUng tim nguon phong xa, tii dong nhan dien dong vi va
do tong suat lieu gamma dua tren pho thu nhan dUdc •
Tai lieu tham khao
[1] Intercomparison between EML method and JAERI method for the measurement of environmental gamma ray exposure rates-Radiation Protection Dosimetry, Vol 18 No 2 pp 81-88 (1987)
[2] JAERI-M 91-204,