content: SECURITIES AND EXCHANGE COMMISSION
  
                               Washington, D.C. 20549
  
                     -------------------------------------------
  
  
                                      FORM 8-K
  
  
                                   CURRENT REPORT
  
                         Pursuant to Section 13 or 15(d) of
                         the Securities Exchange Act of 1934
  
  
  
                                   Date of Report
                         (Date of earliest event reported):
  
                                    April 6, 2000
  
                      ----------------------------------------
  
  
                              THERMEDICS DETECTION INC.
               (Exact name of Registrant as specified in its charter)
  
  
  Massachusetts                      1-12745                           04-3106698
  (State or other                  (Commission                   (I.R.S. Employer
  jurisdiction of                   File Number)            Identification Number)
  incorporation or
  organization)
  
  
  220 Mill Road
  Chelmsford, Massachusetts                                            01824-4178
  (Address of principal executive offices)                            (Zip Code)
  
  
                                   (781) 622-1000
                           (Registrant's telephone number
                                including area code)
  
  
  
  <PAGE>
  
        This Form 8-K contains forward-looking statements that involve a number of
  risks and  uncertainties.  Important  factors that could cause actual results to
  differ  materially from those indicated by such  forward-looking  statements are
  set forth under the heading "Forward-looking  Statements" included in Exhibit 13
  to  Thermedics  Detection  Inc.'s  Annual Report on Form 10-K for the year ended
  January 1, 2000.  These  include  risks and  uncertainties  relating to:  market
  acceptance of new products,  ongoing  product  development  efforts  required by
  rapid technological change, the dependence of the security instruments market on
  government  regulation and the airline  industry,  the  significance  of certain
  customers  to the  Registrant,  as well as risks  associated  with  competition,
  potential product liability,  international  operations,  proprietary technology
  rights,  the  Registrant's  acquisition  strategy,   potential  fluctuations  in
  quarterly performance, dependence on OEM relationships, and the risks associated
  with the Registrant's cash management arrangement with Thermo Electron.
  
  Item 5.     Other Events
  
        On April 7, 2000, the Registrant  issued a press release,  attached hereto
  as Exhibit 99, regarding the previously announced tender offer for its shares of
  common  stock,  $.10 par value per share,  by its ultimate  parent  corporation,
  Thermo Electron Corporation.
  
  Item 7.     Financial Statements, Pro Forma Financial Information and Exhibits
  
        (a)    Financial Statements of Business Acquired: not applicable.
  
        (b)   Pro Forma Financial Information: not applicable.
  
        (c)   Exhibits
  
              99 Press Release dated April 7, 2000.
  
  
  <PAGE>
  
  
                                      SIGNATURE
  
  
  
        Pursuant to the  requirements of the Securities  Exchange Act of 1934, the
  Registrant  has duly  caused  this  report  to be  signed  on its  behalf by the
  undersigned, thereunto duly authorized, on this 7th day of April, 2000.
  
  
                                     THERMEDICS DETECTION INC.
  
  
                                     By:  /s/ Theo Melas-Kyriazi
                                          --------------------------------
                                          Theo Melas-Kyriazi
                                          Chief Financial Officer
  
  
  <PAGE>
  
  
                                                                        Exhibit 99
  
  Investor Contact: 781-622-1111
  Media Contact: 781-622-1252
  
               Cash Tender Offer for Thermedics Detection Completed
  
  CHELMSFORD, Mass., April 7, 2000 - Thermedics Detection Inc. (ASE-TDX), a Thermo
  Electron  company,  announced  today that its parent  company,  Thermedics  Inc.
  (ASE-TMD),  has successfully  completed its cash tender offer of $8.00 per share
  for any and all outstanding shares of Thermedics Detection common stock.
  
        The offer and withdrawal rights expired at midnight on Thursday,  April 6,
  2000. Based on the preliminary report of the depositary for the offer,  American
  Stock Transfer & Trust Company,  approximately 1.9 million Thermedics  Detection
  shares were tendered.  This brings  Thermedics' and Thermo  Electron's  combined
  equity  ownership  in  Thermedics   Detection  to  approximately  98.8  percent.
  Thermedics  expects to complete the spin-in of Thermedics  Detection by Tuesday,
  April 11, through a short-form  merger.  The short-form  merger does not require
  Thermedics Detection board or shareholder approval.
  
        Shareholders  who  tendered  their shares in the tender offer will receive
  payment for their shares shortly.  Shareholders  who did not tender their shares
  will  also  receive  $8.00  per  share  in the  short-form  merger.  Information
  outlining what steps these Thermedics Detection shareholders must take to obtain
  payment will be mailed within a week to 10 days.
  
        The complete terms and conditions of the tender offer are set forth in the
  offer to purchase,  letter of transmittal,  and other related  materials,  which
  were filed with the Securities and Exchange Commission on March 10, 2000.
  
        Thermedics  Detection  develops,   manufactures,  and  markets  high-speed
  systems  used for  product  quality  assurance  in a variety of  industrial  and
  laboratory processes, as well as for security at airports, border crossings, and
  other  checkpoints.   Thermedics  Detection  Inc.  is  a  public  subsidiary  of
  Thermedics Inc., another Thermo Electron company.  More information is available
  on the Internet at http://www.thermo.com/subsid/tdx1.html.
metadata_documents: [{"type": "8-K", "sequence": "1", "description": "FORM 8-K", "secsgml_size_bytes": 5889}]
metadata_filer: {"company-data": {"conformed-name": "THERMEDICS DETECTION INC", "cik": "0001012555", "assigned-sic": "3823", "irs-number": "043106698", "state-of-incorporation": "MA", "fiscal-year-end": "0102"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "001-12745", "film-number": "595820"}, "business-address": {"street1": "220 MILL RD", "city": "CHELMSFORD", "state": "MA", "zip": "01824", "phone": "5082512000"}, "mail-address": {"street1": "220 MILL ROAD", "city": "CHELMSFORD", "state": "MA", "zip": "01824-4178"}}
text: SECURITIES AND EXCHANGE COMMISSION
  
                               Washington, D.C. 20549
  
                     -------------------------------------------
  
                                      FORM 8-K
  
                                   CURRENT REPORT
  
                         Pursuant to Section 13 or 15(d) of
                         the Securities Exchange Act of 1934
  
                                   Date of Report
                         (Date of earliest event reported):
  
                                    April 6, 2000
  
                      ----------------------------------------
  
                              THERMEDICS DETECTION INC.
               (Exact name of Registrant as specified in its charter)
  
  Massachusetts                      1-12745                           04-3106698
  (State or other                  (Commission                   (I.R.S. Employer
  jurisdiction of                   File Number)            Identification Number)
  incorporation or
  organization)
  
  220 Mill Road
  Chelmsford, Massachusetts                                            01824-4178
  (Address of principal executive offices)                            (Zip Code)
  
                                   (781) 622-1000
                           (Registrant's telephone number
                                including area code)
  This Form 8-K contains forward-looking statements that involve a number of
  risks and  uncertainties.  Important  factors that could cause actual results to
  differ  materially from those indicated by such  forward-looking  statements are
  set forth under the heading "Forward-looking  Statements" included in Exhibit 13
  to  Thermedics  Detection  Inc.'s  Annual Report on Form 10-K for the year ended
  January 1, 2000.  These  include  risks and  uncertainties  relating to:  market
  acceptance of new products,  ongoing  product  development  efforts  required by
  rapid technological change, the dependence of the security instruments market on
  government  regulation and the airline  industry,  the  significance  of certain
  customers  to the  Registrant,  as well as risks  associated  with  competition,
  potential product liability,  international  operations,  proprietary technology
  rights,  the  Registrant's  acquisition  strategy,   potential  fluctuations  in
  quarterly performance, dependence on OEM relationships, and the risks associated
  with the Registrant's cash management arrangement with Thermo Electron.
  
  Item 5.     Other Events
  
        On April 7, 2000, the Registrant  issued a press release,  attached hereto
  as Exhibit 99, regarding the previously announced tender offer for its shares of
  common  stock,  $.10 par value per share,  by its ultimate  parent  corporation,
  Thermo Electron Corporation.
  
  Item 7.     Financial Statements, Pro Forma Financial Information and Exhibits
  
        (a)    Financial Statements of Business Acquired: not applicable.
  
        (b)   Pro Forma Financial Information: not applicable.
  
        (c)   Exhibits
  
              99 Press Release dated April 7, 2000.
  SIGNATURE
  
        Pursuant to the  requirements of the Securities  Exchange Act of 1934, the
  Registrant  has duly  caused  this  report  to be  signed  on its  behalf by the
  undersigned, thereunto duly authorized, on this 7th day of April, 2000.
  
                                     THERMEDICS DETECTION INC.
  
                                     By:  /s/ Theo Melas-Kyriazi
                                          --------------------------------
                                          Theo Melas-Kyriazi
                                          Chief Financial Officer
  Exhibit 99
  
  Investor Contact: 781-622-1111
  Media Contact: 781-622-1252
  
               Cash Tender Offer for Thermedics Detection Completed
  
  CHELMSFORD, Mass., April 7, 2000 - Thermedics Detection Inc. (ASE-TDX), a Thermo
  Electron  company,  announced  today that its parent  company,  Thermedics  Inc.
  (ASE-TMD),  has successfully  completed its cash tender offer of $8.00 per share
  for any and all outstanding shares of Thermedics Detection common stock.
  
        The offer and withdrawal rights expired at midnight on Thursday,  April 6,
  2000. Based on the preliminary report of the depositary for the offer,  American
  Stock Transfer & Trust Company,  approximately 1.9 million Thermedics  Detection
  shares were tendered.  This brings  Thermedics' and Thermo  Electron's  combined
  equity  ownership  in  Thermedics   Detection  to  approximately  98.8  percent.
  Thermedics  expects to complete the spin-in of Thermedics  Detection by Tuesday,
  April 11, through a short-form  merger.  The short-form  merger does not require
  Thermedics Detection board or shareholder approval.
  
        Shareholders  who  tendered  their shares in the tender offer will receive
  payment for their shares shortly.  Shareholders  who did not tender their shares
  will  also  receive  $8.00  per  share  in the  short-form  merger.  Information
  outlining what steps these Thermedics Detection shareholders must take to obtain
  payment will be mailed within a week to 10 days.
  
        The complete terms and conditions of the tender offer are set forth in the
  offer to purchase,  letter of transmittal,  and other related  materials,  which
  were filed with the Securities and Exchange Commission on March 10, 2000.
  
        Thermedics  Detection  develops,   manufactures,  and  markets  high-speed
  systems  used for  product  quality  assurance  in a variety of  industrial  and
  laboratory processes, as well as for security at airports, border crossings, and
  other  checkpoints.   Thermedics  Detection  Inc.  is  a  public  subsidiary  of
  Thermedics Inc., another Thermo Electron company.  More information is available
  on the Internet at http://www.thermo.com/subsid/tdx1.html.