# Presentation: 238090

## Calibration Overview – August 31, 2004J. Fishman       

**Calibration Overview**** – August 31, 2004****J. Fishman****       **

## Calibration Plan of the GBM 

- GBM-MPE-PL-1-1, issue date: Dec 2003  >> GBM-PLAN-1016, Baselined at CDR
- By Jerry Fishman and Giselher Lichti
- Purpose
- Outlines the plans for the calibration of the NaI and BGO detectors
- Flight Det. Calib. Performed at three places: MPE, NSSTC and Spectrum Astro
- Ancillary, Off-line Measurements at Low and High Energies
- Generation of detector response matrices (DRMs) for NaIs and BGOs
- Verification of detector-module requirements
**Part I :** Comprehensive Detector Calibrations at MPE :
- 			>TP100 (NaI) ,  TP110 (BGO) &  TP 120 (Mag. Suscept.)
**Part II:** Low Energy X-ray Calibrations with NaI Flight Spare Detector at the PUMA or BESSY X-ray Facility at MPE  - TP 101 (NaI)
**Part III,IV: **Long/Short calibration (TP630/635)   (– these are really verifications)
**Part V: **Aliveness test (TP105/115)
**Part VI: **Spacecraft Radioactive Source Survey (TP805)
**Part VII: **High-Energy Tests with the BGO Flight Spare Detector (TP111)

## Detector-level Calibrations

**1.  Channel-Energy Relation & Energy Resolution at Different Energies (on-axis; covering the whole energy range)**
**2.****	****- Angular Response  – relative values of Efficiency vs. Energy **
**            ****(Used to compare to Monte Carlo Detector Response Matrices, DRMs)**
**3.****	****- Angular Dependence of Energy-Channel Relationship and Energy Resolution    ****(Performed at same time as #2, above)**
**4.****	****- Rate-Dependence of #1 - over several rates, up to 10****5**** cps**** **
**5.****	****- Temperature Dependence of #1, in operating temperature range**

## Detector Magnetic Susceptibility

**GBM-PROC-TP120:**
**In three orthogonal axes, +/- 1.5 gauss**
**Uses radioactive source to measure gain (Na-22)**
**Detailed Procedure outlined in GBM-MPE-PL-11, A. von Kienlin, July 2004**
**Helmholtz coils in MFSA Ottobrunn facility, Germany**
**26 orientations planned**

## Other Calibrations and Related Activities

**Some Calibrations will be verified in Huntsville, after detector delivery and also at the S/C Facility after integration on the spacecraft  (These are termed Long and Short Calibrations)**
**Scattering  Measurements will be made at Spectrum Astro Post-integration to assess spacecraft scattering radiation into the detectors, see PLAN-1016.  Source strengths ~5-10 mC . (Preliminary requirements have been given to Spectrum Astro)**
**The Low Energy Calibrations (~5-35 keV) have several options and are currently under discussion within the GBM team.  **
** ****Some Limited Calibrations at a High-Energy Particle Accelerator  (Perhaps a science model only) –  Duke University is the baselined facility**
**It would be highly desirable to have a quick data run at Spectrum Astro using a portable van de Graff generator (ref. E. Bloom)**

## NaI/BB -  Spectra

**NaI Energy Calibration  - Note linearity and low energy response**

## Low Energy Calibration Sources

**	**
**	**_**Isotope**_**	****	**_**Energy**_
**	****Am-241****	****	****17, 60 keV**
**	**
**	****Cd 109****	****	****22, 88 keV**
**	****Ba-133****	****	****32, 81 keV**
**	****Bi-207****	****	****8, 12, 75 keV**
**	****Co-57****	****	****14 keV**

## Low Energy Calibration – Additional Tests

**	**
**MPE is planning to perform a separate Low Energy Calibration on one or two non-flight NaI detectors  (TP 101) at either PUMA facility at MPE **_**or**_** the BESSY facility in Berlin**
**These tests will be done mainly to explore subtle non-linearities at low energies and across the Iodine k-edge**

## Rate Dependence

- Measurement of rate dependence of
- Channel-Energy Relation
- Energy-Resolution
- as a function of counting rate
- 2  NaI – detectors: (TP100-D)
- 109Cd, increasing count rate in steps up to 100 kcps
- 22Na, increasing count rate in steps up to 20 kcps
- 1  BGO: (TP110 -D)
- 137Cs and 24Na
- Increasing count rate in steps up to 20 kcps

##  Low Energy Tests - The PUMA X-ray Test Facility

- Vacuum system
- Length: 6 m
- Main instrument chamber
- Length:  2 m
- Diameter: 1.6 m
- 10-7 mbar
- Front door opens into class 10 clean room
- Multi-target X-ray source
- produce a bunch of X-rays in the energy range 0.5 – 17 keV
- energy spread: natural line width
- Beam flux: 104 photons/(cm2 s)
- Collimators system inside vacuum tube
- Monitor counters
- silicon drift chamber detectors
- absolutely calibrated
- Accuracy  for spectral flux density  2 %

- GBM test with Puma  (TP 101):
- FM NaI detectors (number: TBD)
- With flight-like thermal cover
- Energy range: 3 – 17 keV
- At different incidence angles

## BGO - High energy tests

- The Duke University Free-Electron Laser Facility (DFELF) will be used for the GBM High Energy Gamma-Ray Calibration
- at the high intensity gamma source location
- utilized for tests of the MPE Mega Project
- calibrations will be performed at least six months prior to launch on the flight spare BGO detector
- test for non-linearity and saturation effects in the BGO crystal and PMT
- energy range:  2 - 35 MeV

**Beam Calibration of the MEGA Prototype ****(****M****edium**** E****nergy**** ****G****amma-Ray**** A****stronomy, 0.4 – 50 MeV)**

- The High Energy Gamma-ray Source at the Free-Electron Laser Lab. (FELL) Duke University, Durham, NC

## Storage Ring, Free Electron laserInverse Compton Beam

**Storage Ring, Free Electron laser****Inverse Compton Beam**

- RF cavity

- wiggler

- mirror

- mirror

- injection

- e--bunch 1

- e--bunch 2

- laser pulse 1

- -ray beam

## The High Intensity -ray Source (HIS)

- free electron laser

## Verifications, not really Calibrations, in Plan #1016 

- Long Calibration (TP 635)
- Purpose: Check gain and resolution of all detectors
- before and after major tests, such as vibration, thermal-vacuum** **
- before and after shipping of the detectors** **
- will be performed at MPE, NSSTC and Spectrum Astro** **
- Short Calibration (TP 630)
- TP 635 with a sub-set of selected detectors** **
- Can be performed at various phases of the integration** **
- Aliveness Test (NaI: TP105, BGO: TP115)
- natural background radiation will be used to ascertain that all detectors are functioning ** **

## Calibration Summary 

| I. Comprehensive   
Detector Calib. & 
Performance  
TP100 (NaI)
TP110 (BGO)
TP 120 (Mag. Suscept.) | All Detectors, including spares | MPE      | 6 keV- 
2.75 MeV | Radioactive Sources
  (complete set) | MPE | NSSTC |
| --- | --- | --- | --- | --- | --- | --- |
| II.  Low Energy X-ray Calibrations 
TP101 | NaI Detectors Only | MPE (PUMA Facility at MPE) | 3-40 keV | X-ray Tube & Filters;
Monochrometer | MPE | NSSTC |
| III.  Short Calibration (Short Performance Verification)
TP630 | As Needed | MPE, NSSTC,
SpectrumAstro | 32 keV – 
1.3 MeV   | Radioactive Sources
  (sub-set) | MPE | NSSTC |
| IV.  Long Calibration (Long Performance Verification)
TP635
TP610 (High Rate) | All Flight Detectors | MPE & NSSTC,
SpectrumAstro | 6 keV- 
2.75 MeV | Radioactive Sources
  (complete set) | MPE | NSSTC |
| V.  Aliveness Test
TP105 (NaI)
TP115 (BGO) | All Flight Detectors | MPE & NSSTC,
SpectrumAstro | Background Radiation only |  -- | MPE | NSSTC |
| VI.  Spacecraft Survey
TP805 | All Flight Detectors  (on the spacecraft) | SpectrumAstro | 32 keV – 
1.3 MeV   | Radioactive Sources
(Cs-137, Co-60 ~5mC) | NSSTC | MPE, SpectrumAstro |
| VII.  High-Energy Test
TP 111 | Non-Flight Detector-BGO only
(Flight Spare Unit) | Duke Univ. (DFEL Facility) | 2.0-30 MeV | Free Electron Laser
 (Inverse Compton) | tbd  | tbd-
Dep. on schedule |

-  ** **_**Test Procedure Development  **_
_**Cal. Element**_** & **_**TP Nos.  Detectors/Type **_** **_**Location of T./C.**_** **_**Energy Range**_**  **_**Sources**_**                **_**Lead**_**        **_**Others**_

## On-Orbit Gain Stabilization System

**Will use 511 keV Background line in an on-board software servo AGC system, similar to that used for BATSE**
**Expected detector count rates and s/w parameters can be derived from BATSE Spectroscopy Detector data**
**Improvements over BATSE on-orbit calibration:**
**Better energy resolution**
**Better background subtraction**
**50 min. integration vs. 5 min. for BATSE  (Requirement: 2% gain stability over an orbit; various contributions to overall reqm’t)**