where expertise comes together - since 1996 -

The Largest Open Access Portal of Nondestructive Testing (NDT)

Conference Proceedings, Articles, News, Exhibition, Forum, Network and more

where expertise comes together
- since 1996 -

1011 views
Technical Discussions
T.J.J.K
T.J.J.K
05:38 Sep-27-2008
Ionization by Radiography

When radiation penetrates a material , depending on energy of radiation electrons are being ejected (Compton,Pairproduction& Photoelectric effect ).

Is this loss a permanent loss & if permanant does the loss of electrons leads to Ionization.

If Ionization happens how does the atom regain the electrons.
( The main process by which the Film is exposed is ejection electron by the radiation as it passes through the lead intensification screen, Does this lead to Ionization of the Intensification screens , Is this Ionization permanent or does it happen?)


    
 
 
N.Kuppusamy
Consultant, NDT Level-III Engineer
Advanced Inspection & Testing (S) Pte Ltd, Singapore, Joined Dec 2003, 34

N.Kuppusamy

Consultant, NDT Level-III Engineer
Advanced Inspection & Testing (S) Pte Ltd,
Singapore,
Joined Dec 2003
34
02:37 Sep-28-2008
Re: Ionization by Radiography
Electron loss in the material is not permanent. It immediately acquired the required electrons from the atmosphere and neighboring atom. The atmosphere replenish their lost ions from cosmic radiation.

The lead screen also replenish their electron from atmosphere when the radiant source is removed. This is called reversible reaction.

But the films made of photosensitive chemicals and they undergo photochemical reaction when exposed to photons (electromagnetic radiation).

When a film is exposed, the Silver from Silver Bromide emulsion is reduced to metallic Silver and Bromine remains in electronegative state (actually the AgBr molecule become polarized to Ag+ and Br- . This photochemical reaction is irreversible and cannot replenish its electron deficiency from atmosphere.

The development process reduces the delta Ag+ to metallic Ag and forms the latent image of the object radiographed. This latent image is fixed and unwanted Br- is removed in the fixer solution.

I learn these details 25 years before in my Level-II course.

Now I wonder how the new generation practitioners lacking this fundamental knowledge even after 25 years of advancement in technology.

Regards,
N.Kuppusamy




    
 
 
chris s
Consultant, qc manager
USA, Joined Apr 2007, 9

chris s

Consultant, qc manager
USA,
Joined Apr 2007
9
07:40 Sep-29-2008
Re: Ionization by Radiography
----------- Start Original Message -----------
: Electron loss in the material is not permanent. It immediately acquired the required electrons from the atmosphere and neighboring atom. The atmosphere replenish their lost ions from cosmic radiation.
: The lead screen also replenish their electron from atmosphere when the radiant source is removed. This is called reversible reaction.
: But the films made of photosensitive chemicals and they undergo photochemical reaction when exposed to photons (electromagnetic radiation).
: When a film is exposed, the Silver from Silver Bromide emulsion is reduced to metallic Silver and Bromine remains in electronegative state (actually the AgBr molecule become polarized to Ag+ and Br- . This photochemical reaction is irreversible and cannot replenish its electron deficiency from atmosphere.
: The development process reduces the delta Ag+ to metallic Ag and forms the latent image of the object radiographed. This latent image is fixed and unwanted Br- is removed in the fixer solution.
: I learn these details 25 years before in my Level-II course.
: Now I wonder how the new generation practitioners lacking this fundamental knowledge even after 25 years of advancement in technology.
: Regards,
: N.Kuppusamy
------------ End Original Message ------------

Everyone has to start somewhere. Not everyone is as endowed as you sir.


    
 
 
Nick Welland
Other, Quality and NDT
Aben Technical Services, Australia, Joined Oct 1999, 42

Nick Welland

Other, Quality and NDT
Aben Technical Services,
Australia,
Joined Oct 1999
42
09:34 Oct-01-2008
Re: Ionization by Radiography
----------- Start Original Message -----------
: : Electron loss in the material is not permanent. It immediately acquired the required electrons from the atmosphere and neighboring atom. The atmosphere replenish their lost ions from cosmic radiation.
: : The lead screen also replenish their electron from atmosphere when the radiant source is removed. This is called reversible reaction.
: : But the films made of photosensitive chemicals and they undergo photochemical reaction when exposed to photons (electromagnetic radiation).
: : When a film is exposed, the Silver from Silver Bromide emulsion is reduced to metallic Silver and Bromine remains in electronegative state (actually the AgBr molecule become polarized to Ag+ and Br- . This photochemical reaction is irreversible and cannot replenish its electron deficiency from atmosphere.
: : The development process reduces the delta Ag+ to metallic Ag and forms the latent image of the object radiographed. This latent image is fixed and unwanted Br- is removed in the fixer solution.
: : I learn these details 25 years before in my Level-II course.
: : Now I wonder how the new generation practitioners lacking this fundamental knowledge even after 25 years of advancement in technology.
: : Regards,
: : N.Kuppusamy
: Everyone has to start somewhere. Not everyone is as endowed as you sir.
------------ End Original Message ------------

Knowledge is not endowed, it is worked for. The loss of fundamental knowledge is not restricted to our own field; stories abound that some first-year university students are functionally illiterate, which news I find frightening.
I ascribe much of the decline to the philosophy of "teaching to the exam" where the object is to gain a qualification rather than knowledge per se.
We "stand on the shoulders of giants", but it behoves us to ensure that a cadre is educated to carry on!
Regards,
NW


    
 
 

Product Spotlight

Lyft™: Pulsed Eddy Current Reinvented

PEC Reinvented—CUI Programs Redefined Corrosion under insulation (CUI) is possibly the greatest u
...
nresolved asset integrity problem in the industry. Current methods for measuring wall thickness with liftoff, without removing insulation, all have severe limitations. Eddyfi introduces Lyft — a reinvented, high-performance pulsed eddy current (PEC) solution. The patent- pending system features a state-of-the-art portable instrument, real- time C-scan imaging, fast data acquisition with grid-mapping and dynamic scanning modes, and flexibility with long cables. It can also scan through thick metal and insulation, as well as aluminum, stainless steel, and galvanized steel weather jackets. Who else but Eddyfi to reinvent an eddy current technique and redefine CUI programs. Got Lyft?
>

NEW - TD Focus-ScanRX

The NEW Next Generation Advanced UT platform, TD Focus ScanRX - Also available as a card stack solut
...
ion. Key Improvements 1. Data acquisition is significantly faster than current design 2. Better aesthetic – closely aligns with HandyScan RX 3. Improved IP rating (Target IP66) 4. Ruggedized housing 5. Connectors are protected from impact and ingress 6. Integrated stand and separate retractable handle easy to keep clean) 7. Touchscreen with ruggedized display glass 8. 3-Axis encoder input
>

TVC awarded UKAS accreditation

TVC are delighted to finally announce we have been awarded UKAS accreditation for our calibration
...
laboratory. Laboratory accreditation to ISO/IEC 17025:2005 enables us to conduct the Electrical Verification of Ultrasonic Flaw Detection Equipment to BS EN 12668-1:2010. It has taken many months of hard work and we want to thank our staff for all their efforts during this massive undertaking.
>

Immersion systems

ScanMaster ultrasonic immersion systems are designed for high throughput, multi shift operation in a
...
n industrial or lab environment. These fully integrated systems provide various scanning configurations and incorporate conventional and phased arrays technologies to support diverse applications, such as inspection of disks, bars, shafts, billets and plates. All of ScanMaster immersion systems are built from high accuracy scanning frames allowing for scanning of complex parts and include a multi-channel ultrasonic instrument with exceptional performance. The systems are approved by all major manufacturers for C-scan inspection of jet engine forged discs. Together with a comprehensive set of software modules these flexible series of systems provide the customer with the best price performance solutions.
>

Share...
We use technical and analytics cookies to ensure that we will give you the best experience of our website - More Info
Accept
top
this is debug window