STEREO/IMPACT/SIT

Alpha Test

Test Procedure

Ver. 1.1 07/21/05

Unit: Test: Date:

Recorded by:
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1\. PURPOSE

This document specifies the procedure for performing the SIT alpha test
following the instrument thermal vacuum (TV) test. The alpha test checks
the end-to-end performance of the SIT sensor. It is intended for use in
high vacuum environments only: the HVPS can only be turned on in high
vacuum

2\. REQUIREMENTS

2.1 Equipment -- A radioactive alpha source (typically 241Am) is
required, mounted in front of the telescope opening and aimed directly
into the center of the foil, perpendicular to the foil surface. The SIT
door must be open, since the alphas cannot penetrate the door.

3\. PROCEDURE

NOTE: It is unnecessary to repeat commands between procedures if they
would simply put SIT in the state it is already in.

**3.1 Instrument Power On and Initialization**

When instrument has been pumped down to rough vacuum (\< 1 T) check that
the alpha sources are properly aimed by turning on the instrument BUT
NOT the HIGH VOLTAGE.

a)  Turn on instrument

b)  If loading code from SEP Central EEPROM, verify EEPROM checksum
    before proceeding.

  ------------------ -------------------------- --------------------------
  **Description**    **Expected Value**         **Actual Value**

  Tab cksm           927143 (04/25/05)          
  ------------------ -------------------------- --------------------------

c)  If loading code from a file, verify correct file being used.

d\) Begin login of SIT data into a dated file.

**Log Filename**
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

e\) Verify SEP Bias supply is ON

f\) If running from the SIT UMd GSE, verify that SSD bias is on.

g\) Check that SSD count rate is \> 100 counts/sec in order to verify
that alpha source is properly aimed

h\) turn instrument off, and pump down to high vacuum.

i\) close log file

**3.2 Instrument Power On and Initialization**

Verify instrument has been in vacuum \< 1e-6 Torr for \> 12 hours
\_\_\_\_\_\_\_

NOTE DATE AND TIME:
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

> a\) Turn on instrument

b)  If loading code from SEP Central EEPROM, verify EEPROM checksum
    before proceeding.

  ------------------ -------------------------- --------------------------
  **Description**    **Expected Value**         **Actual Value**

  Tab cksm           927143 (04/25/05)          
  ------------------ -------------------------- --------------------------

c)  If loading code from a file, verify correct file being used.

d\) Begin login of SIT data into a dated file.

**Log Filename**
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

e\) Verify SEP Bias supply is ON

f\) If running from the SIT UMd GSE, verify that SSD bias is on.

Send the SIT Commands:

**immed 1**

**hvenable 1**

**CAUTION: the following is a hazardous command. Check carefully before
sending**

**hvramp 80**

> After 2-3 minutes, verify the HV setting \--

  ------------------ --------------------- ------------------ --------------
  **Description**    **Expected Value**    **Actual Value**   **Comments**

  HV Step            80                                       

  HV                 2800-3050                                

  HV Status          1 = on                                   
  ------------------ --------------------- ------------------ --------------

Send the SIT Command:

**CAUTION: the following is a hazardous command. Check carefully before
sending**

**hvramp 90**

> After 2-3 minutes, verify the HV setting \--

  ------------------ --------------------- ------------------ --------------
  **Description**    **Expected Value**    **Actual Value**   **Comments**

  HV Step            90                                       

  HV                 2800-3050                                

  HV Status          1 = on                                   
  ------------------ --------------------- ------------------ --------------

Send the SIT Command:

**CAUTION: the following is a hazardous command. Check carefully before
sending**

**hvramp a0**

> After 2-3 minutes, verify the HV setting \--

  ------------------ --------------------- ------------------ --------------
  **Description**    **Expected Value**    **Actual Value**   **Comments**

  HV Step            A0                                       

  HV                 3200-3500                                

  HV Status          1 = on                                   
  ------------------ --------------------- ------------------ --------------

Send the SIT Command:

**CAUTION: the following is a hazardous command. Check carefully before
sending**

**hvramp a8**

> After 2-3 minutes, verify the HV setting \--

  ------------------ --------------------- ------------------ --------------
  **Description**    **Expected Value**    **Actual Value**   **Comments**

  HV Step            A8                                       

  HV                 3500-3650                                

  HV Status          1 = on                                   
  ------------------ --------------------- ------------------ --------------

Send the SIT Command:

**CAUTION: the following is a hazardous command. Check carefully before
sending**

**hvramp b0**

> After 2-3 minutes, verify the HV setting \--

  ------------------ --------------------- ------------------ --------------
  **Description**    **Expected Value**    **Actual Value**   **Comments**

  HV Step            b0                                       

  HV                 3650-3800                                

  HV Status          1 = on                                   
  ------------------ --------------------- ------------------ --------------

Send the SIT Command:

**CAUTION: the following is a hazardous command. Check carefully before
sending**

**hvramp b8**

> After 2-3 minutes, verify the HV setting \--

  ------------------ --------------------- ------------------ --------------
  **Description**    **Expected Value**    **Actual Value**   **Comments**

  HV Step            B8                                       

  HV                 3800-3950                                

  HV Status          1 = on                                   
  ------------------ --------------------- ------------------ --------------

> The high voltage step b8 is the normal operating voltage for the alpha
> run.
>
> Continue to collect data for 10-15 minutes.

Send the SIT Command:

**CAUTION: the following is a hazardous command. Check carefully before
sending**

**hvramp 0**

**hvenable 0**

> After 2-3 minutes, verify the HV setting \--

  ------------------ --------------------- ------------------ --------------
  **Description**    **Expected Value**    **Actual Value**   **Comments**

  HV Step            00                                       

  HV                 0                                        

  HV Status          0 = off                                  
  ------------------ --------------------- ------------------ --------------

> Stop recording log file.
>
> Power down instrument
>
> END OF TEST