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From: YANG Tao <yangt_at_ihep.ac.cn>

Date: Sat, 12 Sep 2015 08:14:04 +0800 (GMT+08:00)

Dear Fasso,

Thanks for your reply. I will read these references.

Regards,

Tao Yang.

-----原始邮件-----

发件人: "Fasso, Alberto" <fasso_at_slac.stanford.edu>

发送时间: 2015年9月12日 星期六

收件人: "YANG Tao" <yangt_at_ihep.ac.cn>, "Mikhail Polkovnikov <Михаил Полковников>" <pmk_at_ihep.ru>

抄送: "fluka-discuss_at_fluka.org" <fluka-discuss_at_fluka.org>

主题: Re: Re: [fluka-discuss]: what is the meaning of Mean Excitation Energy

The mean excitation energy (or mean excitation potential) is a quantity appearing

in the Bethe-Bloch formula for stopping power. Look at the Wikipedia article on

"Bethe formula".

The value for Ar is indeed 188 eV, as you can check on many databases, for instance on http://physics.nist.gov/PhysRefData/XrayMassCoef/tab1.html

To understand its physical meaning, look at http://pdg.lbl.gov/2014/AtomicNuclearProperties/adndt.pdf :

"The electronic stopping power is calculated by summing the contributions of all possible inelastic scatterings. These are normally from lower to higher (bound or unbound) electronic energy states, so the particle loses a small amount of energy in each scattering."

A simplified expression for the mean excitation energy I is given by:

In(I)=Integral(df/dE lnE dE) /Integral(df/dE dE)

where df/dE is the density of optical dipole oscillator strength f per unit

energy of excitation E above the ground state and the integrals include summations over the discrete states.

(See http://www.osti.gov/scitech/servlets/purl/6733705-roWoV2/ )

Alberto

From:owner-fluka-discuss_at_mi.infn.it <owner-fluka-discuss_at_mi.infn.it> on behalf of YANG Tao <yangt_at_ihep.ac.cn>

Sent: Friday, September 11, 2015 5:54 AM

To: Mikhail Polkovnikov <Михаил Полковников>

Cc:fluka-discuss_at_fluka.org

Subject: Re: Re: [fluka-discuss]: what is the meaning of Mean Excitation Energy

Dear Mikhail,

Thanks for your answer. But what is the mean excitation energy? Is it the average value of all the excitation energies? And what's its relation with the physical quantity--- "the average energy expenditure per ion pair"?

regards,

Tao Yang

-----原始邮件-----

发件人: "Mikhail Polkovnikov <Михаил Полковников>" <pmk_at_ihep.ru>

发送时间: 2015年9月11日 星期五

收件人: "YANG Tao" <yangt_at_ihep.ac.cn>, "fluka-discuss_at_fluka.org" <fluka-discuss_at_fluka.org>

抄送:

主题: Re: [fluka-discuss]: what is the meaning of Mean Excitation Energy

On 11.09.2015 13:22, YANG Tao wrote:

Hi, everyone!

When I look the output(.out) of FLUKA, I find that the mean excitation energy of Ar is 188 eV, but the excitation energy of Ar is 15.7 eV which can be found anywhere. I try to find the definition of the mean excitation energy, unfortunately, I cannot find it. Could anyone can tell me the meaning of the two physical quantities?

regards,

Tao Yang

Dear Tao Yang,

The energy 15.7 eV is the least bond energy for upper shell electron (http://xdb.lbl.gov/Section1/Table_1-1.pdf)

Best regards,

Mikhail

Date: Sat, 12 Sep 2015 08:14:04 +0800 (GMT+08:00)

Dear Fasso,

Thanks for your reply. I will read these references.

Regards,

Tao Yang.

-----原始邮件-----

发件人: "Fasso, Alberto" <fasso_at_slac.stanford.edu>

发送时间: 2015年9月12日 星期六

收件人: "YANG Tao" <yangt_at_ihep.ac.cn>, "Mikhail Polkovnikov <Михаил Полковников>" <pmk_at_ihep.ru>

抄送: "fluka-discuss_at_fluka.org" <fluka-discuss_at_fluka.org>

主题: Re: Re: [fluka-discuss]: what is the meaning of Mean Excitation Energy

The mean excitation energy (or mean excitation potential) is a quantity appearing

in the Bethe-Bloch formula for stopping power. Look at the Wikipedia article on

"Bethe formula".

The value for Ar is indeed 188 eV, as you can check on many databases, for instance on http://physics.nist.gov/PhysRefData/XrayMassCoef/tab1.html

To understand its physical meaning, look at http://pdg.lbl.gov/2014/AtomicNuclearProperties/adndt.pdf :

"The electronic stopping power is calculated by summing the contributions of all possible inelastic scatterings. These are normally from lower to higher (bound or unbound) electronic energy states, so the particle loses a small amount of energy in each scattering."

A simplified expression for the mean excitation energy I is given by:

In(I)=Integral(df/dE lnE dE) /Integral(df/dE dE)

where df/dE is the density of optical dipole oscillator strength f per unit

energy of excitation E above the ground state and the integrals include summations over the discrete states.

(See http://www.osti.gov/scitech/servlets/purl/6733705-roWoV2/ )

Alberto

From:owner-fluka-discuss_at_mi.infn.it <owner-fluka-discuss_at_mi.infn.it> on behalf of YANG Tao <yangt_at_ihep.ac.cn>

Sent: Friday, September 11, 2015 5:54 AM

To: Mikhail Polkovnikov <Михаил Полковников>

Cc:fluka-discuss_at_fluka.org

Subject: Re: Re: [fluka-discuss]: what is the meaning of Mean Excitation Energy

Dear Mikhail,

Thanks for your answer. But what is the mean excitation energy? Is it the average value of all the excitation energies? And what's its relation with the physical quantity--- "the average energy expenditure per ion pair"?

regards,

Tao Yang

-----原始邮件-----

发件人: "Mikhail Polkovnikov <Михаил Полковников>" <pmk_at_ihep.ru>

发送时间: 2015年9月11日 星期五

收件人: "YANG Tao" <yangt_at_ihep.ac.cn>, "fluka-discuss_at_fluka.org" <fluka-discuss_at_fluka.org>

抄送:

主题: Re: [fluka-discuss]: what is the meaning of Mean Excitation Energy

On 11.09.2015 13:22, YANG Tao wrote:

Hi, everyone!

When I look the output(.out) of FLUKA, I find that the mean excitation energy of Ar is 188 eV, but the excitation energy of Ar is 15.7 eV which can be found anywhere. I try to find the definition of the mean excitation energy, unfortunately, I cannot find it. Could anyone can tell me the meaning of the two physical quantities?

regards,

Tao Yang

Dear Tao Yang,

The energy 15.7 eV is the least bond energy for upper shell electron (http://xdb.lbl.gov/Section1/Table_1-1.pdf)

Best regards,

Mikhail

-- 杨涛 中科院高能所东莞分部（东莞中子科学中心）加速器技术部 地址：东莞市大朗镇中子源路1号中国散裂中子源A2栋606室 E-mail：yangt_at_ihep.ac.cn 电话：0769-38944239 邮编：523803 -- 杨涛 中科院高能所东莞分部（东莞中子科学中心）加速器技术部 地址：东莞市大朗镇中子源路1号中国散裂中子源A2栋606室 E-mail：yangt_at_ihep.ac.cn 电话：0769-38944239 邮编：523803 __________________________________________________________________________ You can manage unsubscription from this mailing list at https://www.fluka.org/fluka.php?id=acc_infoReceived on Sat Sep 12 2015 - 03:56:05 CEST

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