{"id":1054,"date":"2020-09-12T18:26:58","date_gmt":"2020-09-12T23:26:58","guid":{"rendered":"http:\/\/maximus.energy\/?p=1054"},"modified":"2022-10-20T13:59:20","modified_gmt":"2022-10-20T18:59:20","slug":"snmo-5-bf3-neutron-detector","status":"publish","type":"post","link":"https:\/\/maximus.energy\/index.php\/2020\/09\/12\/snmo-5-bf3-neutron-detector\/","title":{"rendered":"SNMO-5 BF3 Neutron Detector"},"content":{"rendered":"\n

SNMO-5<\/a> is a neutron detector (proportional counter) filled with boron trifluoride enriched with boron-10 – Fig. 1. The tube is 10.5″ long and has a diameter of 1.375″. These dimensions are comparable to the size of helium-3 filled SNM-18 tube<\/a>. BF3 gas pressure in SNMO-5, however, is rather low, 1\/3 atm.<\/p>\n\n\n\n

\"SNMO-5
Fig. 1. SNMO-5 boron trifluoride-filled neutron detector.<\/figcaption><\/figure>\n\n\n\n

Due to the fairly low gas pressure the sensitivity of SNMO-5 tube to thermal neutrons as measured with 5 mCi Po-Be source is only ~1 CPS. This is not impressive and amounts to about 10% of the sensitivity of SNM-18 helium-3 filled tube, which has almost identical dimensions. SNMO-5 low sensitivity is almost entirely caused by the much lower gas pressure (1\/3 atm) vs. 2-3 atm in SNM-18. Sensitivity reduction due to boron-10 is a relatively minor factor: boron-10 has ~30% lower cross section for capturing thermal neutrons compared to helium-3.<\/p>\n\n\n\n

Thermal neutron spectrum of SNMO-5 is shown on Fig. 2. X-ray peak is evident in the first few channels of the spectrum. Thermal neutron peak is non-existent due to low gas pressure.<\/p>\n\n\n\n

\"\"
Fig. 2. SNMO-5 thermal neutron spectrum. X-ray peak dominates the first few channels of the spectrum.<\/figcaption><\/figure>\n\n\n\n

Conclusion<\/h2>\n\n\n\n

Given the availability of reasonably priced SNM-18 counter tubes<\/a> it makes no sense to go with boron trifluoride, especially at low pressure.<\/p>\n","protected":false},"excerpt":{"rendered":"

SNMO-5 is a neutron detector (proportional counter) filled with boron trifluoride enriched with boron-10 – Fig. 1. The tube is 10.5″ long and has a diameter of 1.375″. These dimensions are comparable to the size of helium-3 filled SNM-18 tube. BF3 gas pressure in SNMO-5, however, is rather low, 1\/3 atm. Due to the fairly […]<\/p>\n","protected":false},"author":1,"featured_media":1055,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[20],"tags":[],"class_list":["post-1054","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-neutron-detection"],"jetpack_publicize_connections":[],"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p9osz2-h0","jetpack_likes_enabled":true,"jetpack-related-posts":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/maximus.energy\/wp-content\/uploads\/2020\/09\/SNMO-5.jpg?fit=1857%2C402&ssl=1","_links":{"self":[{"href":"https:\/\/maximus.energy\/index.php\/wp-json\/wp\/v2\/posts\/1054","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/maximus.energy\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/maximus.energy\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/maximus.energy\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/maximus.energy\/index.php\/wp-json\/wp\/v2\/comments?post=1054"}],"version-history":[{"count":3,"href":"https:\/\/maximus.energy\/index.php\/wp-json\/wp\/v2\/posts\/1054\/revisions"}],"predecessor-version":[{"id":1059,"href":"https:\/\/maximus.energy\/index.php\/wp-json\/wp\/v2\/posts\/1054\/revisions\/1059"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/maximus.energy\/index.php\/wp-json\/wp\/v2\/media\/1055"}],"wp:attachment":[{"href":"https:\/\/maximus.energy\/index.php\/wp-json\/wp\/v2\/media?parent=1054"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/maximus.energy\/index.php\/wp-json\/wp\/v2\/categories?post=1054"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/maximus.energy\/index.php\/wp-json\/wp\/v2\/tags?post=1054"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}