{"id":5012,"date":"2020-04-20T15:08:42","date_gmt":"2020-04-20T08:08:42","guid":{"rendered":"https:\/\/vinatom.gov.vn\/?p=5012"},"modified":"2020-04-20T15:08:42","modified_gmt":"2020-04-20T08:08:42","slug":"xac-dinh-do-am-cua-dat-thong-qua-thong-luong-neutron-vu-tru","status":"publish","type":"post","link":"https:\/\/vinatom.gov.vn\/xac-dinh-do-am-cua-dat-thong-qua-thong-luong-neutron-vu-tru\/","title":{"rendered":"X\u00e1c \u0111\u1ecbnh \u0111\u1ed9 \u1ea9m c\u1ee7a \u0111\u1ea5t th\u00f4ng qua th\u00f4ng l\u01b0\u1ee3ng neutron v\u0169 tr\u1ee5"},"content":{"rendered":"

\u0110\u1ed9 \u1ea9m \u0111\u1ea5t \u0111\u01b0\u1ee3c bi\u1ec3u th\u1ecb b\u1eb1ng t\u1ef7 l\u1ec7 ph\u1ea7n tr\u0103m tr\u1ecdng l\u01b0\u1ee3ng c\u1ee7a n\u01b0\u1edbc trong \u0111\u1ea5t so v\u1edbi tr\u1ecdng l\u01b0\u1ee3ng \u0111\u1ea5t. \u0110\u1ed9 \u1ea9m \u0111\u1ea5t c\u00f2n \u0111\u01b0\u1ee3c bi\u1ec3u th\u1ecb b\u1eb1ng t\u1ef7 s\u1ed1 ph\u1ea7n tr\u0103m dung t\u00edch n\u01b0\u1edbc trong \u0111\u1ea5t so v\u1edbi t\u1ed5ng th\u1ec3 t\u00edch c\u1ee7a \u0111\u1ea5t. Khi \u0111\u1ed9 \u1ea9m \u0111\u1ea5t th\u1ea5p h\u01a1n m\u1ed9t gi\u1edbi h\u1ea1n n\u00e0o \u0111\u00f3, th\u1ef1c v\u1eadt kh\u00f4ng h\u00fat \u0111\u1ee7 n\u01b0\u1edbc th\u00ec s\u1ebd b\u1ecb h\u1ea1n. \u0110\u1ed9 \u1ea9m c\u1ee7a \u0111\u1ea5t l\u00e0 m\u1ed9t th\u00f4ng s\u1ed1 quan tr\u1ecdng trong chu tr\u00ecnh th\u1ee7y v\u0103n v\u00e0 t\u00e1c \u0111\u1ed9ng \u0111\u1ebfn nhi\u1ec1u \u1ee9ng d\u1ee5ng kh\u00e1c nhau, bao g\u1ed3m c\u1ea3 qu\u1ea3n l\u00fd n\u00f4ng nghi\u1ec7p, gi\u00e1m s\u00e1t s\u1ef1 thay \u0111\u1ed5i m\u00f4i tr\u01b0\u1eddng (b\u00e3o c\u00e1t v\u00e0 x\u00f3i m\u00f2n), \u1ee9ng d\u1ee5ng kh\u00ed h\u1eadu v\u00e0 th\u1eddi ti\u1ebft, d\u1ef1 \u0111o\u00e1n thi\u00ean tai (l\u0169 l\u1ee5t v\u00e0 h\u1ea1n h\u00e1n) v\u00e0 t\u00e1i t\u1ea1o n\u01b0\u1edbc ng\u1ea7m. Tuy nhi\u00ean, \u0111\u1ed9 \u1ea9m c\u1ee7a \u0111\u1ea5t l\u00e0 m\u1ed9t th\u00f4ng s\u1ed1 kh\u00f3 theo d\u00f5i v\u00e0 \u0111o l\u01b0\u1eddng li\u00ean t\u1ee5c \u1edf quy m\u00f4 l\u01b0u v\u1ef1c v\u00ec c\u00e1c \u0111\u1eb7c \u0111i\u1ec3m kh\u00f4ng \u0111\u1ed3ng nh\u1ea5t c\u1ee7a n\u00f3. N\u00f3 thay \u0111\u1ed5i c\u1ea3 v\u1ec1 kh\u00f4ng gian v\u00e0 th\u1eddi gian v\u00e0 do \u0111\u00f3 l\u00e0 m\u1ed9t ngu\u1ed3n t\u00e0i nguy\u00ean \u0111\u1ed9ng. Hi\u1ec7n nay, c\u00f3 h\u00e0ng t\u00e1 ph\u01b0\u01a1ng ph\u00e1p \u0111o \u0111\u1ed9 \u1ea9m \u0111\u1ea5t, c\u00e1c ph\u01b0\u01a1ng ph\u00e1p truy\u1ec1n th\u1ed1ng \u0111\u1ec3 \u0111o \u0111\u1ed9 \u1ea9m c\u1ee7a \u0111\u1ea5t bao g\u1ed3m ph\u01b0\u01a1ng ph\u00e1p s\u1ea5y, ph\u01b0\u01a1ng ph\u00e1p th\u1ec3 t\u00edch th\u1ef1c t\u1ebf, ph\u01b0\u01a1ng ph\u00e1p tr\u1ecdng l\u1ef1c ri\u00eang, ph\u01b0\u01a1ng ph\u00e1p tia, ph\u01b0\u01a1ng ph\u00e1p t\u00ednh ch\u1ea5t \u0111i\u1ec7n m\u00f4i,… M\u1eb7c d\u00f9 c\u00e1c ph\u01b0\u01a1ng ph\u00e1p n\u00e0y c\u00f3 th\u1ec3 \u01b0\u1edbc t\u00ednh ch\u00ednh x\u00e1c \u0111\u1ed9 \u1ea9m c\u1ee7a \u0111\u1ea5t, ch\u00fang l\u00e0 c\u00e1c ph\u01b0\u01a1ng ph\u00e1p \u0111o \u0111i\u1ec3m v\u1edbi c\u00e1c thang \u0111o nh\u1ecf, v\u00e0 k\u1ebft qu\u1ea3 \u0111o ch\u1ec9 c\u00f3 th\u1ec3 bi\u1ec3u th\u1ecb tr\u1ea1ng th\u00e1i \u0111\u1ed9 \u1ea9m c\u1ee7a \u0111\u1ea5t \u1edf \u0111i\u1ec3m n\u00e0y, v\u00ec v\u1eady \u0111\u1ea1i di\u1ec7n kh\u00f4ng gian l\u00e0 nh\u1ecf. Do t\u00ednh kh\u00f4ng \u0111\u1ed3ng nh\u1ea5t c\u1ee7a \u0111\u1ea5t, ph\u01b0\u01a1ng ph\u00e1p \u0111o \u0111i\u1ec3m truy\u1ec1n th\u1ed1ng ch\u1ec9 c\u00f3 th\u1ec3 \u0111\u00e1p \u1ee9ng c\u00e1c y\u00eau c\u1ea7u b\u1eb1ng c\u00e1ch t\u0103ng l\u00ean di\u1ec7n t\u00edch l\u1edbn h\u01a1n theo t\u1ef7 l\u1ec7. Do \u0111\u00f3, c\u1ea7n c\u00f3 \u0111\u1ee7 d\u1eef li\u1ec7u \u0111o \u0111i\u1ec3m \u0111\u1ec3 t\u00ednh to\u00e1n, l\u00e0m t\u0103ng \u0111\u00e1ng k\u1ec3 chi ph\u00ed v\u00e0 ch\u1ec9 c\u00f3 th\u1ec3 v\u1ec1 m\u1eb7t k\u1ef9 thu\u1eadt. Vi\u1ec7c s\u1eed d\u1ee5ng ph\u01b0\u01a1ng ph\u00e1p vi\u1ec5n th\u00e1m \u0111\u1ec3 theo d\u00f5i \u0111\u1ed9 \u1ea9m \u0111\u1ea5t \u1edf n\u01b0\u1edbc ngo\u00e0i b\u1eaft \u0111\u1ea7u t\u1eeb cu\u1ed1i nh\u1eefng n\u0103m 1960, v\u00e0 trong nh\u1eefng n\u0103m 1970, nghi\u00ean c\u1ee9u theo d\u00f5i \u0111\u1ed9 \u1ea9m \u0111\u1ea5t b\u1eb1ng vi\u1ec5n th\u00e1m \u0111\u00e3 \u0111\u1ea1t \u0111\u01b0\u1ee3c s\u1ef1 ph\u00e1t tri\u1ec3n nhanh ch\u00f3ng v\u00e0 to\u00e0n di\u1ec7n. C\u00f4ng ngh\u1ec7 vi\u1ec5n th\u00e1m c\u00f3 c\u00e1c \u01b0u \u0111i\u1ec3m nh\u01b0 xem x\u00e9t nhanh, \u0111\u1ed9 t\u01b0\u01a1ng ph\u1ea3n \u0111\u1ed9ng m\u1ea1nh, gi\u00e1m s\u00e1t di\u1ec7n r\u1ed9ng \u0111\u1ed9ng d\u00e0i h\u1ea1n v\u00e0 \u0111\u1ed9 ph\u00e2n gi\u1ea3i kh\u00f4ng gian-th\u1eddi gian t\u1ed1t, nh\u01b0ng n\u00f3 c\u0169ng c\u00f3 nh\u01b0\u1ee3c \u0111i\u1ec3m nh\u01b0 \u0111\u1ed9 s\u00e2u \u0111o n\u00f4ng, kh\u1ea3 n\u0103ng \u0111\u00e2m xuy\u00ean k\u00e9m, \u0111\u1ed9 nh\u1ea1y k\u00e9m, v\u00e0 th\u1eddi gian bay c\u1ee7a v\u1ec7 tinh ng\u1eafn.<\/p>\n

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Vi\u1ec7c k\u1ebft h\u1ee3p c\u00e1c k\u1ef9 thu\u1eadt v\u00e0 c\u00f4ng ngh\u1ec7 m\u1edbi v\u00e0o qu\u1ea3n l\u00fd t\u00e0i nguy\u00ean n\u00f4ng nghi\u1ec7p c\u00f3 kh\u1ea3 n\u0103ng c\u1ea3i thi\u1ec7n kh\u1ea3 n\u0103ng c\u1ee7a n\u00f4ng d\u00e2n, c\u00e1c nh\u00e0 khoa h\u1ecdc v\u00e0 c\u00e1c nh\u00e0 ho\u1ea1ch \u0111\u1ecbnh ch\u00ednh s\u00e1ch trong vi\u1ec7c \u0111\u1ea3m b\u1ea3o an ninh l\u01b0\u01a1ng th\u1ef1c. Ch\u01b0\u01a1ng tr\u00ecnh Qu\u1ea3n l\u00fd \u0111\u1ea5t v\u00e0 n\u01b0\u1edbc & dinh d\u01b0\u1ee1ng c\u00e2y tr\u1ed3ng c\u1ee7a m\u1ed9t B\u1ed9 ph\u1eadn chung gi\u1eefa T\u1ed5 ch\u1ee9c n\u00f4ng l\u01b0\u01a1ng th\u1ebf gi\u1edbi (FAO) v\u00e0 C\u01a1 quan N\u0103ng l\u01b0\u1ee3ng nguy\u00ean t\u1eed qu\u1ed1c t\u1ebf (IAEA) \u0111\u00e3 t\u1eadp trung v\u00e0o ph\u00e1t tri\u1ec3n c\u00e1c c\u00f4ng ngh\u1ec7 v\u00e0 th\u1ef1c ti\u1ec5n qu\u1ea3n l\u00fd c\u00e2y tr\u1ed3ng, n\u01b0\u1edbc, v\u00e0 c\u1ea3i ti\u1ebfn \u0111\u1ec3 t\u0103ng c\u01b0\u1eddng n\u00f4ng nghi\u1ec7p b\u1ec1n v\u1eefng th\u00f4ng qua vi\u1ec7c s\u1eed d\u1ee5ng c\u00e1c k\u1ef9 thu\u1eadt h\u1ea1t nh\u00e2n v\u00e0 th\u00f4ng th\u01b0\u1eddng. K\u1ef9 thu\u1eadt h\u1ea1t nh\u00e2n v\u00e0 c\u00e1c k\u1ef9 thu\u1eadt li\u00ean quan c\u00f3 th\u1ec3 gi\u00fap ph\u00e1t tri\u1ec3n c\u00e1c gi\u1ea3i ph\u00e1p th\u1ef1c h\u00e0nh n\u00f4ng nghi\u1ec7p th\u00edch \u1ee9ng v\u1edbi kh\u00ed h\u1eadu b\u1eb1ng c\u00e1ch t\u1ed1i \u01b0u h\u00f3a hi\u1ec7u qu\u1ea3 s\u1eed d\u1ee5ng n\u01b0\u1edbc. Vi\u1ec7c \u0111o h\u00e0m l\u01b0\u1ee3ng n\u01b0\u1edbc trong \u0111\u1ea5t l\u00e0 r\u1ea5t c\u1ea7n thi\u1ebft \u0111\u1ec3 c\u1ea3i thi\u1ec7n vi\u1ec7c s\u1eed d\u1ee5ng t\u00e0i nguy\u00ean n\u00e0y trong n\u00f4ng nghi\u1ec7p. C\u00e1c thi\u1ebft b\u1ecb \u0111o t\u1ef7 l\u1ec7 r\u1ed9ng h\u01a1n l\u00e0 c\u1ea7n thi\u1ebft thay th\u1ebf cho ph\u01b0\u01a1ng ph\u00e1p ti\u1ebfp c\u1eadn \u0111i\u1ec3m truy\u1ec1n th\u1ed1ng.<\/p>\n

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Trong nh\u1eefng n\u0103m g\u1ea7n \u0111\u00e2y, c\u00f4ng ngh\u1ec7 \u0111o \u0111\u1ed9 \u1ea9m \u0111\u1ea5t khu v\u1ef1c b\u1eb1ng ph\u01b0\u01a1ng ph\u00e1p neutron v\u0169 tr\u1ee5 \u0111\u00e3 \u0111\u01b0\u1ee3c ph\u00e1t tri\u1ec3n nhanh ch\u00f3ng. Tia v\u0169 tr\u1ee5 s\u01a1 c\u1ea5p l\u00e0 c\u00e1c h\u1ea1t n\u0103ng l\u01b0\u1ee3ng cao c\u00f3 ngu\u1ed3n g\u1ed1c t\u1eeb ngo\u00e0i v\u0169 tr\u1ee5 v\u00e0 li\u00ean t\u1ee5c b\u1eafn ph\u00e1 tr\u00e1i \u0111\u1ea5t. C\u01b0\u1eddng \u0111\u1ed9 c\u1ee7a c\u00e1c tia v\u0169 tr\u1ee5 \u0111\u1ebfn \u0111\u1ec9nh kh\u00ed quy\u1ec3n tr\u00e1i \u0111\u1ea5t thay \u0111\u1ed5i theo c\u00e1c s\u1ef1 ki\u1ec7n t\u1ea1o ra ch\u00fang (s\u1ef1 ki\u1ec7n thi\u00ean v\u0103n xa x\u00f4i) v\u00e0 c\u00e1c y\u1ebfu t\u1ed1 nh\u01b0 s\u1ef1 bi\u1ebfn \u0111\u1ed5i trong t\u1eeb quy\u1ec3n m\u1eb7t tr\u1eddi. C\u00e1c h\u1ea1t ch\u1ee7 y\u1ebfu l\u00e0 (90%) proton (P) v\u1edbi n\u0103ng l\u01b0\u1ee3ng \u0111i\u1ec3n h\u00ecnh kho\u1ea3ng 1 GeV. Khi c\u00e1c h\u1ea1t n\u00e0y \u0111i v\u00e0o b\u1ea7u kh\u00ed quy\u1ec3n tr\u00e1i \u0111\u1ea5t, ch\u00fang va ch\u1ea1m v\u1edbi c\u00e1c nguy\u00ean t\u1eed trong kh\u00f4ng kh\u00ed v\u00e0 t\u1ea1o ra m\u1ed9t c\u01a1n m\u01b0a c\u00e1c h\u1ea1t tia v\u0169 tr\u1ee5 th\u1ee9 c\u1ea5p (bao g\u1ed3m c\u1ea3 neutron), c\u00f3 th\u1ec3 ho\u1eb7c kh\u00f4ng th\u1ec3 t\u01b0\u01a1ng t\u00e1c v\u1edbi c\u00e1c h\u1ea1t kh\u00e1c tr\u01b0\u1edbc khi ch\u1ea1m t\u1edbi b\u1ec1 m\u1eb7t tr\u00e1i \u0111\u1ea5t. M\u1ed7i va ch\u1ea1m l\u00e0m cho h\u1ea1t (neutron) m\u1ea5t n\u0103ng l\u01b0\u1ee3ng. C\u00e1c t\u01b0\u01a1ng t\u00e1c ph\u1ee9c h\u1ee3p n\u00e0y \u0111\u01b0\u1ee3c mi\u00eau t\u1ea3 nh\u01b0 \u1edf tr\u00ean h\u00ecnh 1a. Ph\u1ed5 n\u0103ng l\u01b0\u1ee3ng c\u1ee7a c\u00e1c neutron n\u00e0y \u1edf b\u1ec1 m\u1eb7t tr\u00e1i \u0111\u1ea5t ch\u1ee9a m\u1ed9t s\u1ed1 \u0111\u1ec9nh. \u1ede kho\u1ea3ng 100 MeV l\u00e0 c\u00e1c neutron n\u0103ng l\u01b0\u1ee3ng cao, ch\u00fang t\u01b0\u01a1ng t\u00e1c v\u1edbi kh\u00f4ng kh\u00ed v\u00e0 \u0111\u1ea5t \u0111\u1ec3 t\u1ea1o ra \u0111\u1ec9nh th\u1ee9 hai, \u1edf kho\u1ea3ng 1 MeV, c\u1ee7a neutron nhanh, c\u00f2n \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 neutron bay h\u01a1i (\u0111\u00f3 kh\u00f4ng ph\u1ea3i l\u00e0 s\u1ef1 b\u1ed1c h\u01a1i theo c\u00e1ch hi\u1ec3u c\u1ee7a c\u00e1c nh\u00e0 th\u1ee7y v\u0103n nh\u01b0ng vi\u1ec7c ph\u00e1t ra c\u00e1c h\u1ea1t neutron sau s\u1ef1 va ch\u1ea1m c\u1ee7a h\u1ea1t n\u0103ng l\u01b0\u1ee3ng cao, v\u00ed d\u1ee5. m\u1ed9t proton ho\u1eb7c neutron, v\u1edbi h\u1ea1t nh\u00e2n c\u1ee7a m\u1ed9t nguy\u00ean t\u1eed).<\/p>\n

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$\"\"$ H\u00ecnh 1. C\u00e1c t\u01b0\u01a1ng t\u00e1c neutron ph\u1ee9c h\u1ee3p \u0111\u01b0\u1ee3c c\u1ea3m bi\u1ebfn ph\u00e1t hi\u1ec7n\u00a0<\/em>v\u00e0 chuy\u1ec3n th\u00e0nh \u01b0\u1edbc t\u00ednh \u0111\u1ed9 \u1ea9m c\u1ee7a \u0111\u1ea5t<\/em><\/p>\n

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Nh\u1eefng va ch\u1ea1m h\u01a1n n\u1eefa l\u00e0m gi\u1ea3m n\u0103ng l\u01b0\u1ee3ng c\u1ee7a neutron h\u01a1n n\u1eefa cho \u0111\u1ebfn khi ch\u00fang tr\u1edf th\u00e0nh b\u1ecb \u2018nhi\u1ec7t h\u00f3a\u2019 t\u1ee9c l\u00e0 \u1edf tr\u1ea1ng th\u00e1i c\u00e2n b\u1eb1ng nhi\u1ec7t v\u1edbi m\u00f4i tr\u01b0\u1eddng; \u0111\u00f3 l\u00e0 ch\u00fang kh\u00f4ng th\u1ec3 m\u1ea5t nhi\u1ec1u n\u0103ng l\u01b0\u1ee3ng h\u01a1n c\u0169ng nh\u01b0 kh\u00f4ng l\u1ea5y l\u1ea1i \u0111\u01b0\u1ee3c n\u0103ng l\u01b0\u1ee3ng. Nh\u1eefng neutron nhi\u1ec7t ho\u1eb7c b\u1ecb nhi\u1ec7t h\u00f3a n\u00e0y c\u00f3 n\u0103ng l\u01b0\u1ee3ng \u0111i\u1ec3n h\u00ecnh kho\u1ea3ng 0,1 eV. C\u00e1c neutron c\u00f3 n\u0103ng l\u01b0\u1ee3ng l\u1edbn h\u01a1n neutron nhi\u1ec7t c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 tr\u00ean nhi\u1ec7t, th\u01b0\u1eddng c\u00f3 ngh\u0129a l\u00e0 l\u1edbn h\u01a1n 0,5 eV; do \u0111\u00f3 neutron nhanh n\u1eb1m trong d\u1ea3i tr\u00ean nhi\u1ec7t. Ph\u1ed5 n\u0103ng l\u01b0\u1ee3ng n\u00e0y \u0111\u01b0\u1ee3c minh h\u1ecda nh\u01b0 tr\u00ean h\u00ecnh 2.<\/p>\n

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$\"\"$ H\u00ecnh 2. Ph\u1ed5 n\u0103ng l\u01b0\u1ee3ng neutron \u1edf b\u1ec1 m\u1eb7t \u0111o \u0111\u01b0\u1ee3c (m\u00e0u x\u00e1m) v\u00e0 \u0111\u01b0\u1ee3c m\u00f4 ph\u1ecfng (n\u00e9t \u0111\u1ee9t). Sau khi tr\u1eeb th\u00e0nh ph\u1ea7n ph\u1ea3n x\u1ea1 m\u1eb7t \u0111\u1ea5t qua n\u01b0\u1edbc tinh khi\u1ebft, ch\u00fang ta c\u00f3 \u0111\u01b0\u1ee3c m\u1ed9t th\u00e0nh ph\u1ea7n thu\u1ea7n t\u00fay (\u0111\u01b0\u1eddng m\u00e0u \u0111en li\u00ean t\u1ee5c), \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng l\u00e0m ph\u1ed5 ngu\u1ed3n. M\u00e0u s\u1eafc minh h\u1ecda s\u1ef1 l\u00e0m ch\u1eadm c\u1ee7a neutron n\u0103ng l\u01b0\u1ee3ng cao ban \u0111\u1ea7u (m\u00e0u \u0111\u1ecf), t\u01b0\u01a1ng t\u00e1c v\u1edbi c\u00e1c nguy\u00ean t\u1eed n\u1eb7ng d\u1eabn \u0111\u1ebfn ph\u1ed5 bay h\u01a1i (m\u00e0u xanh l\u00e1 c\u00e2y). N\u0103ng l\u01b0\u1ee3ng b\u1ecb m\u1ea5t do va ch\u1ea1m \u0111\u00e0n h\u1ed3i v\u1edbi c\u00e1c nguy\u00ean t\u1eed nh\u1eb9 n\u01a1i m\u00e0 \u0111\u1ea7u d\u00f2 \u0111\u1eb7c bi\u1ec7t nh\u1ea1y (m\u00e0u xanh) cho \u0111\u1ebfn khi neutron \u0111\u1ea1t \u0111\u1ebfn n\u0103ng l\u01b0\u1ee3ng \u1edf tr\u1ea1ng th\u00e1i c\u00e2n b\u1eb1ng nhi\u1ec7t (m\u00e0u x\u00e1m nh\u1ea1t)<\/em><\/p>\n

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Qu\u00e1 tr\u00ecnh nhi\u1ec7t h\u00f3a neutron (c\u0169ng \u0111\u01b0\u1ee3c bi\u1ebft nh\u01b0 l\u00e0 qu\u00e1 tr\u00ecnh l\u00e0m ch\u1eadm) ph\u1ee5 thu\u1ed9c ch\u1ee7 y\u1ebfu v\u00e0o t\u00ednh ch\u1ea5t c\u1ee7a c\u00e1c h\u1ea1t (hay nguy\u00ean t\u1ed1) m\u00e0 tia v\u0169 tr\u1ee5 va ch\u1ea1m v\u00e0o. Hydrogen l\u00e0 nguy\u00ean t\u1ed1 hi\u1ec7u qu\u1ea3 nh\u1ea5t v\u1ec1 kh\u1ea3 n\u0103ng h\u00e3m neutron nhanh; 18 va ch\u1ea1m v\u1edbi hydro s\u1ebd nhi\u1ec7t h\u00f3a m\u1ed9t neutron nhanh trong khi \u0111i\u1ec1u n\u00e0y m\u1ea5t 149 va ch\u1ea1m v\u1edbi oxy. \u0110i\u1ec1u n\u00e0y \u0111\u01b0\u1ee3c gi\u1ea3i th\u00edch b\u1edfi th\u1ef1c t\u1ebf l\u00e0 h\u1ea1t nh\u00e2n hydro nh\u1eb9, ch\u1ec9 bao g\u1ed3m m\u1ed9t proton, c\u00f3 th\u1ec3 h\u1ea5p th\u1ee5 r\u1ea5t nhi\u1ec1u n\u0103ng l\u01b0\u1ee3ng t\u1eeb neutron trong m\u1ed9t l\u1ea7n va ch\u1ea1m, trong khi \u0111\u00f3 khi m\u1ed9t neutron ch\u1ea1m v\u00e0o m\u1ed9t h\u1ea1t nh\u00e2n l\u1edbn, n\u00f3 s\u1ebd b\u1eadt ra v\u00e0 gi\u1eef l\u1ea1i ph\u1ea7n l\u1edbn n\u0103ng l\u01b0\u1ee3ng c\u1ee7a n\u00f3. N\u0103ng l\u01b0\u1ee3ng h\u00e3m n\u00e0y k\u1ebft h\u1ee3p v\u1edbi s\u1ef1 phong ph\u00fa c\u1ee7a hydro trong kh\u00f4ng kh\u00ed v\u00e0 \u0111\u1ea5t c\u00f3 ngh\u0129a l\u00e0 qu\u00e1 tr\u00ecnh nhi\u1ec7t h\u00f3a ph\u1ea7n l\u1edbn \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh b\u1edfi s\u1ef1 hi\u1ec7n di\u1ec7n c\u1ee7a hydro.<\/p>\n

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Nh\u1eefng va ch\u1ea1m n\u00e0y d\u1eabn \u0111\u1ebfn neutron b\u1ecb t\u00e1n x\u1ea1 theo m\u1ecdi h\u01b0\u1edbng, t\u1ee9c l\u00e0 gi\u1eefa v\u00e0 trong kh\u00f4ng kh\u00ed v\u00e0 \u0111\u1ea5t, v\u00e0 qu\u00e1 tr\u00ecnh nhi\u1ec7t h\u00f3a c\u00f3 hi\u1ec7u qu\u1ea3 t\u1ee9c th\u1eddi v\u00ec n\u0103ng l\u01b0\u1ee3ng\/v\u1eadn t\u1ed1c cao c\u1ee7a c\u00e1c neutron nhanh. Do \u0111\u00f3 n\u1ed3ng \u0111\u1ed9 neutron nhanh mau ch\u00f3ng \u0111\u1ea1t \u0111\u1ebfn tr\u1ea1ng th\u00e1i c\u00e2n b\u1eb1ng trong c\u1ea3 \u0111\u1ea5t v\u00e0 kh\u00f4ng kh\u00ed, v\u00e0 m\u1ed9t y\u1ebfu t\u1ed1 quan tr\u1ecdng trong vi\u1ec7c x\u00e1c \u0111\u1ecbnh n\u1ed3ng \u0111\u1ed9 l\u00e0 l\u01b0\u1ee3ng hi\u1ec7n di\u1ec7n c\u1ee7a hydro. C\u00e1c neutron n\u0103ng l\u01b0\u1ee3ng cao th\u00f4ng qua c\u00e1c tia v\u0169 tr\u1ee5, b\u1ecb l\u00e0m ch\u1eadm v\u00e0 \u0111\u01b0\u1ee3c h\u1ea5p th\u1ee5 m\u1ed9t ph\u1ea7n b\u1edfi c\u00e1c nguy\u00ean t\u1eed hydro c\u1ee7a n\u01b0\u1edbc trong \u0111\u1ea5t\u2013 m\u1ed9t s\u1ed1 neutron n\u0103ng l\u01b0\u1ee3ng th\u1ea5p b\u1ecb t\u00e1n x\u1ea1 ng\u01b0\u1ee3c tr\u1edf l\u1ea1i t\u1eeb \u0111\u1ea5t (h\u00ecnh 1b). M\u1ed9t thi\u1ebft b\u1ecb g\u1ecdi l\u00e0 c\u1ea3m bi\u1ebfn neutron v\u0169 tr\u1ee5 CRNS nh\u01b0 h\u00ecnh 3 (Cosmic Ray Neutron Sensing) \u0111\u01b0\u1ee3c ch\u1ebf t\u1ea1o \u0111\u1ec3 li\u00ean t\u1ee5c \u0111\u1ebfm nh\u1eefng neutron n\u00e0y. Khi \u0111\u1ed9 \u1ea9m \u0111\u1ea5t t\u0103ng, \u00edt neutron tho\u00e1t ra kh\u1ecfi \u0111\u1ea5t, v\u00e0 do \u0111\u00f3 t\u1ed1c \u0111\u1ed9 \u0111\u1ebfm gi\u1ea3m neutron ghi nh\u1eadn \u0111\u01b0\u1ee3c gi\u1ea3m. \u0110\u00e2y l\u00e0 c\u01a1 s\u1edf c\u1ee7a ph\u01b0\u01a1ng ph\u00e1p \u0111o \u0111\u1ed9 \u1ea9m \u0111\u1ea5t th\u00f4ng qua th\u00f4ng l\u01b0\u1ee3ng neutron v\u0169 tr\u1ee5. CRNS \u1edf b\u1ec1 m\u1eb7t \u0111\u1ea5t s\u1ebd \u0111\u1ebfm \u0111\u01b0\u1ee3c nhi\u1ec1u neutron nhanh h\u01a1n khi c\u00f3 \u00edt hydro (n\u01b0\u1edbc) v\u00e0 \u00edt neutron nhanh h\u01a1n khi c\u00f3 nhi\u1ec1u hydro h\u01a1n \u0111\u1ec3 l\u1ea5y n\u0103ng l\u01b0\u1ee3ng t\u1eeb neutron d\u1eabn \u0111\u1ebfn s\u1ef1 nhi\u1ec7t h\u00f3a ch\u00fang.<\/p>\n

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$\"\"$ H\u00ecnh 3. Nguy\u00ean l\u00fd ho\u1ea1t \u0111\u1ed9ng v\u00e0 \u0111\u1eb7c tr\u01b0ng k\u1ef9 thu\u1eadt c\u1ee7a c\u1ea3m bi\u1ebfn neutron v\u0169 tr\u1ee5 CRNS \u0111\u1ec3 theo d\u00f5i \u0111\u1ed9 \u1ea9m c\u1ee7a \u0111\u1ea5t<\/em><\/p>\n

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Nh\u01b0 v\u1eady, \u0111\u1ed9 \u1ea9m c\u1ee7a \u0111\u1ea5t c\u00f3 th\u1ec3 x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1ee3c b\u1eb1ng c\u00e1ch \u0111o c\u01b0\u1eddng \u0111\u1ed9 c\u1ee7a neutron g\u1ea7n m\u1eb7t \u0111\u1ea5t sau khi l\u00e0m ch\u1eadm. Ph\u01b0\u01a1ng ph\u00e1p hay k\u1ef9 thu\u1eadt n\u00e0y c\u00f3 c\u00e1c \u0111\u1eb7c \u0111i\u1ec3m nh\u01b0 \u0111\u1ed9 che ph\u1ee7 kh\u00f4ng gian l\u1edbn v\u00e0 y\u00eau c\u1ea7u th\u1ea5p v\u1ec1 \u0111\u1ed9 m\u1eb7n c\u1ee7a \u0111\u1ea5t, m\u1eadt \u0111\u1ed9 \u0111\u1ea5t, k\u1ebft c\u1ea5u \u0111\u1ea5t, v.v., v\u1edbi ph\u1ea1m vi \u0111o t\u1ed1i \u0111a kho\u1ea3ng 670 m v\u00e0 \u0111\u1ed9 s\u00e2u \u0111o \u0111\u01b0\u1ee3c l\u00e0 12 ~ 76 cm qua t\u00ednh to\u00e1n v\u00e0 \u0111o \u0111\u1ea1c th\u1ef1c t\u1ebf. C\u1ea3m bi\u1ebfn neutron v\u0169 tr\u1ee5 (CRNS) l\u00e0 m\u1ed9t thi\u1ebft b\u1ecb theo d\u00f5i h\u00e0m l\u01b0\u1ee3ng n\u01b0\u1edbc trong \u0111\u1ea5t theo c\u00e1ch kh\u00f4ng x\u00e2m l\u1ea5n, kh\u00f4ng nguy hi\u1ec3m v\u00e0 li\u00ean t\u1ee5c. Thi\u1ebft b\u1ecb \u0111\u01b0\u1ee3c ph\u00e1t tri\u1ec3n g\u1ea7n \u0111\u00e2y c\u00f3 th\u1ec3 \u0111\u1ec3 \u0111o h\u00e0m l\u01b0\u1ee3ng n\u01b0\u1edbc trong l\u1edbp \u0111\u1ea5t m\u1eb7t tr\u00ean c\u00e1c khu v\u1ef1c r\u1ed9ng, c\u00f3 di\u1ec7n t\u00edch l\u00ean t\u1edbi 30 ha. N\u00f3 l\u1ea5p \u0111\u1ea7y kho\u1ea3ng tr\u1ed1ng trong vi\u1ec7c \u0111o \u0111\u1ed9 \u1ea9m c\u1ee7a \u0111\u1ea5t tr\u00ean c\u00e1c khu v\u1ef1c r\u1ed9ng l\u1edbn \u0111\u1ec3 qu\u1ea3n l\u00fd n\u01b0\u1edbc n\u00f4ng nghi\u1ec7p t\u1ed1t h\u01a1n. V\u1edbi c\u00e1c t\u00ednh n\u0103ng \u01b0u vi\u1ec7t c\u1ee7a k\u1ef9 thu\u1eadt \u0111o \u0111\u1ed9 \u1ea9m \u0111\u1ea5t th\u00f4ng qua th\u00f4ng l\u01b0\u1ee3ng neutron v\u0169 tr\u1ee5 v\u00e0 c\u00e1c l\u1ee3i \u00edch to l\u1edbn m\u00e0 n\u00f3 mang l\u1ea1i, c\u00e1c qu\u1ed1c gia nh\u01b0 Hoa K\u1ef3, \u00dac, \u0110\u1ee9c v\u00e0 V\u01b0\u01a1ng qu\u1ed1c Anh \u0111\u00e3 \u0111\u1ea7u t\u01b0 r\u1ea5t l\u1edbn v\u00e0o c\u00f4ng ngh\u1ec7 n\u00e0y v\u00e0 \u0111\u00e3 t\u1ea1o ra m\u1ea1ng l\u01b0\u1edbi quan tr\u1eafc \u0111\u1ed9 \u1ea9m \u0111\u1ea5t qu\u1ed1c gia.<\/p>\n

\u00a0<\/strong><\/p>\n

Nguy\u1ec5n \u0110\u1ee9c Tu\u1ea5n,\u00a0<\/strong>Vi\u1ec7n Khoa h\u1ecdc & K\u1ef9 thu\u1eadt h\u1ea1t nh\u00e2n<\/strong><\/p>\n

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T\u00e0i li\u1ec7u tham kh\u1ea3o<\/strong><\/em><\/p>\n

Cosmic-ray soil moisture sensor:<\/p>\n

https:\/\/cosmos.ceh.ac.uk\/CosmicRaySensor<\/a><\/p>\n

Footprint Characteristics of Cosmic-Ray Neutron Sensors for Soil Moisture Monitoring:<\/p>\n

http:\/\/www.ufz.de\/index.php?en=33719&posterfilter=footprint<\/a><\/p>\n

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