Dr. SaMeH S. Ahmed

Associate Prof. of Environmental Engineering

Ionizing radiation

Ionizing radiation


Ionizing (or ionisingradiation is radiation composed of particles that individually can liberate an electron from anatom or molecule, producing ions, which are atoms or molecules with a net electric charge. These ions tend to be especially chemically reactive, and the reactivity produces the high biological damage per unit of energy that is a characteristic of all ionizing radiation.

The degree and nature of such ionization depends on the energy and type of the individual particles composing the radiation, and less upon the radiation particle number. For example, if a non-ionizing type of radiation does not heat a bulk substance up to ionization temperature, even an intense flood of particles or particle-waves will not cause ionization. In such cases, each particle or particle-wave does not carry enough individual energy to be ionizing (an example is a high-powered radio or microwave beam, which will not ionize if it does not cause high temperatures). Conversely, even very low-intensity radiation will ionize materials at low temperatures and powers, if the individual particles of radiation carry enough energy (e.g., a low-power X-ray beam). These radiations are termed "ionizing." In general, particles or photons with energies above about 10 electron volts (eV) (some sources require 33 eV) are considered ionizing, no matter what their intensity. This particle-energy occurs in electromagnetic waves in for X-raysand gamma rays, and also the extreme part of the ultraviolet spectrum (not all ultraviolet is ionizing).

Free neutrons are able to cause many nuclear reactions in a variety of substances no matter their energy, because in many substances they give rise to high-energy nuclear reactions, and these (or their products) liberate enough energy to cause ionization. For this reason, free neutrons are normally considered effectively ionizing radiation, at any energy (see neutron radiation). Examples of other ionizing particles are alpha particlesbeta particles, and cosmic rays. The radiations cause ionization due to the kinetic energy involved in the production of the individual particles, which inevitably exceed the threshold of 10 or 33 eV, and commonly exceed thousands or even millions of eV of energy.

Lower-energy radiation, such as visible light, infrared, microwaves, and radio waves, are not ionizing. The latter types of low-energy non-ionizing radiation may damage molecules, but the effect is generally indistinguishable from the effects of simple heating. Such heating does not produce free radicals until higher temperatures (for example, flame temperatures or "browning" temperatures, and above) are attained. In contrast, ionizing radiation produces free radicals, such as reactive oxygen species, even at room temperatures and below. Free radical production is a primary basis for the particular danger to biological systems of relatively small amounts of ionizing radiation that are far smaller than needed to produce significant heating. Free radicals easily damage DNA, and ionizing radiation may also directly damage DNA by ionizing or breaking DNA molecules.

Radiobiologists see a degree of overlap between truly ionizing radiation and the lower ultraviolet (UV) spectrum from 3.1 to 10 eV that contains molecularly-damaging radiation that is not formally ionizing, but has somewhat similar biological effects that are larger than are predictable from thermal considerations alone. Non-ionizing ultraviolet can also cause damage to skin as a result of photoreactions in collagen. DNA molecules may also be directly or indirectly damaged by UV radiation carrying enough energy to excite certain molecular bonds to form thymine dimers (pyrimidine dimer)s (this causes sunburn).

Ionizing radiation is ubiquitous in the environment, and comes from naturally occurring radioactive materials and cosmic rays. Common artificial sources are artificially produced radioisotopes, X-ray tubes and particle accelerators. Ionizing radiation is invisible and not directly detectable by human senses, so instruments such as Geiger counters are usually required to detect its presence. In some cases it may lead to secondary emission of visible light upon interaction with matter, such as in Cherenkov radiation and radioluminescence. It has many practical uses in medicine, research, construction, and other areas, but presents a health hazard if used improperly. Exposure to ionizing radiation causes damage to living tissue, and can result in mutationradiation sickness,cancer, and death.

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For CE 370 students : I do apologize for did not attend the extra lab session that proposed to be on Wednesday at 6 am.  Sorry

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Please visit the  announcement box for the relevant course and make sure that you can download and upload easily, otherwise

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There will be an orientation session in the midell of this term to help you select your track in Civil and Environmental Engineering


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Electrical Power Resources: Coal versus Renewable Energy

  Published Online on January 2016

Mining Engineering

Mining engineering is an engineering discipline that involves practice, theory, science, technology, and the application of extracting and processing minerals from a naturally occurring environment. Mining engineering also includes processing minerals for additional value.

Environmental Engineering

Environmental engineers are the technical professionals who identify and design solutions for    environmental problems. Environmental engineers provide safe drinking water, treat and properly dispose of wastes, maintain air quality, control water pollution, and remediate sites contaminated due to spills or improper disposal of hazardous substances. They monitor the quality of the air, water, and land. And, they develop new and improved means to protect the environment.


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College of Eng. MU



Universities I've worked in

Assuit University (Home University), Egypt

Imperial College, London, UK

Faculty of Engineering, Al-Mergeb University, Libya

King Saud University, KSA

,Majmaah University

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Course 2016/17-1

  1. Computer Applications in Surveying  CE 473
  2. Surveying 1 CE 370
  3. Photogrammetry CE 474
  4. Surveying II  CE 371
  5. Design I  (round 4) CE 498

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Member of the Editorial Board: " Journal of Water Resources and Ocean Sciences"  2013


Participating in The Third International Conference on Water, Energy and Environment,(ICWEE) 2015 - American University of Sharjah, UAE 24-26 March 2015 with a Paper and Poster

New article

Recovery of Titania from Waste-Sludge of Majmaah Water Treatment Plant

"Production of Titania Nano-particles from Wast-


Coming soon

Results of M2 CE311

Student Conference

Participation  in the 6Th Student Conference

With a paper and oral presentation

From the Senior Design Project CE499 -35

See inside, the paper, and presentation

CE 370 Course

Surveying  I -  CE 370 - 2016-2017-1

Power point


Lecture notes

Second Midterm Exam


Model Answer
Inside, please follow:

Student Performance Records

CE 371 Course

Surveying II - CE 371 - 2016-2017-1


First midterm exam



See Inside

Student Performance Records

CE473 Course

Computer Applications in Surveying

CE 473


Power point


Exams + Quizzes


CE 474 Course

2015-2016-2 - Photogrammetry  CE474

Available 0-1-2-3-4 Power point


Quizzes 2 and 3 with model Answer

Available Chapter 1,2,3,4,5 Lecture notes

Report 1  Cameras Report


60 marks Exams

See Inside

Student Performance Records

CE 360 Course

Environmental Engineering 1

CE 360: Environmental Engineering 1


Y PP0-1-2-3,4 Power point
Y 1,2,3,4,5 Chapters

Water quality Poster + Climate Change Reports
will be announced (Quiz #2 will be using D2L- Online Quizzes


Quizzez 2,3 and 4 with model answer and results Exams and results

GE 306 Course

Engineering Report Writing

GE 306: Engineering Report Writing

CE 499 Course

Senior Design 2 - CE 499

Meeting on 14-4-2015

Second Best paper from Senior Design Projects in 2015

Paper title:

Evaluation of Groundwater Quality Parameters using Multivariate Statistics- a case Study of Majmaah, KSA


Abdullah A. Alzeer

Husam K. Almubark

Maijd M. Almotairi

CE 360-Summer Course

Environmental Engineering I

Welcome to CE360 second Term 2015-2016 

Engineering Practice

 Engineering Practice GE 307

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Civil and Environmental Engineering Department
College of Engineering, Majmaah University
Majmaah, P.O. 66, 11952, KSA

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Your frequent visit to my website has helped  a lot to get the 2nd place in the university competition in the  year 1434-2013... Thanks very mush and please keep following my work

زيارتكم المتكررة لموقعي ساهمت في حصولي على المركز الثاني لاحسن المواقع الشخصية بجامعة المجمعة ...لكم جميعا خالص شكري وتقديري

CE 212 - Summer Course

Properties and Strength of Materials 1

CE 212

Y from PP0 to PP 6 + PDF Power points
Y Midterm #2 + Model Answer + results Exams
Y lab 3 Labs

Solution of Quiz 4 + Results HW

CE 311- Summer Course

Soil Mechanics and Foundation Engineering

CE 311

M2+ model Answer + PP 1-9 = PDF 1-9 all are available

Sheets 2 + 4 with model Answers

Results of M2

إحصائية الموقع

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