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<p>I too shall miss Dan very much. I did not know him until our
encounters during LCTG meetings. I enjoyed our conversations,
together with Charlie! One of the more memorable meetings was when
we were at a LCTG luncheon with our wives, the six of us sat
together and all were able to pass pleasantries with each other.
He will be missed by many and I'm sure his legacy will endure. So
sad!!</p>
<p>-Dick<br>
</p>
<div class="moz-cite-prefix">On 6/30/2025 2:14 PM, Shireen Ahmed via
LCTG wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAKsE78z-6CfS1+_G+XbYTR59CJE9fA=khgesdYws6EQOjiSBEw@mail.gmail.com">
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<div dir="ltr">
<div dir="ltr">So sorry to hear about Dan's passing. I did not
know him, just read about him, certainly a very
accomplished scientist.
<div><br>
</div>
<div>- Shireen Ahmed</div>
</div>
<br>
<div class="gmail_quote gmail_quote_container">
<div dir="ltr" class="gmail_attr">On Mon, Jun 30, 2025 at
1:57 PM Michael Alexander via LCTG <<a
href="mailto:lctg@lists.toku.us" moz-do-not-send="true"
class="moz-txt-link-freetext">lctg@lists.toku.us</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
I first encountered Dan when he was “Dr. Kleppner” to me —
when he taught one-third of Harvard’s three-sem<span>ester
introductory physics sequence (he also was a member of
Professor Norman Ramsey’s research group). It probably
was the first formal course that Dan taught. He was a
good lecturer; but what impressed me most strongly,
then, was the sense of responsibility to students
that he displayed when he lectured: he really *tried*.</span>
<div><br>
I therefore looked forward to each presentation Dan (no
longer “Dr. Kleppner”) gave to our Computer Group, and
never was disappointed.</div>
<div><br>
</div>
<div> — Mike Alexander<br>
<div><br>
</div>
<br>
<p
style="font-size:15px;color:rgb(123,106,246);padding-top:15px;margin-top:0px">On
Monday, June 30, 2025, 12:21 PM, Ted Kochanski via
LCTG <<a href="mailto:lctg@lists.toku.us"
target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">lctg@lists.toku.us</a>>
wrote:</p>
<blockquote>
<div id="m_2522374105748133428yiv3165671766">
<div>
<div dir="ltr">All,
<div><br clear="none">
</div>
<div><br clear="none">
</div>
<div>I met Dan when I was an MIT undergraduate
-- long before I knew of the existence of the
LCTG</div>
<div><br clear="none">
</div>
<div>Dan also was sort of the Intellectual
Grandfather to my brother Greg for his Ph.D.
research "Magnetic Trapping and Cooling of
Atomic Hydrogen" MIT 1987 </div>
<div><br clear="none">
</div>
<div>Dan founded the lab and pioneered the
cooling process that my brother used for his
work with Spin Polarized Hydrogen</div>
<div>see for example:</div>
<div><br clear="none">
</div>
<div>Magnetic Trapping of Spin-Polarized Atomic
Hydrogen<br clear="none">
Harald F. Hess, Greg P. Kochanski, John M.
Doyle, Naoto Masuhara, Daniel Kleppner and
Thomas J. Greytak<br clear="none">
Copyright (c) 1987 The Japan Society of
Applied Physics<br clear="none">
Japanese Journal of Applied Physics, Volume
26, Number S3-1<br clear="none">
Citation Harald F. Hess et al 1987 Jpn. J.
Appl. Phys. 26 237<br clear="none">
DOI 10.7567/JJAPS.26S3.237</div>
<div><br clear="none">
</div>
<div>and</div>
<div><br clear="none">
</div>
<div>Evaporative Cooling of Spin-Polarized
Atomic Hydrogen<br clear="none">
Naoto Masuhara, John M. Doyle, Jon C.
Sandberg, Daniel Kleppner, Thomas J.
Greytak, Harald F. Hess and Greg P. Kochanski<br
clear="none">
Publisher website<br clear="none">
21 August 1988<br clear="none">
Published by American Physical Society (APS)
in Physical Review Letters<br clear="none">
Vol. 61 (8) , 935-938<br clear="none">
<a rel="nofollow noopener noreferrer"
shape="rect"
href="https://doi.org/10.1103/physrevlett.61.935" target="_blank"
moz-do-not-send="true"
class="moz-txt-link-freetext">https://doi.org/10.1103/physrevlett.61.935</a></div>
<div><br clear="none">
</div>
<div>and</div>
<div><br clear="none">
</div>
<div>“Temperature and magnetic field dependence
of three-body recombination in spin polarized
hydrogen;” </div>
<div>H. F. Hess, D. A. Bell, G. P. Kochanski, D.
A. Kleppner, T. J. Greytak, 1984 Phys. Rev.
Lett. 52, 1520–1523</div>
<div><br clear="none">
and</div>
<div><br clear="none">
“Observation of three-body recombination in
spin-polarized hydrogen;” H. F. Hess,<br
clear="none">
D. A. Bell, G. P. Kochanski, R. W. Cline, D.
A. Kleppner, T. J. Greytak, 1983<br
clear="none">
Phys. Rev. Lett. 51, 483–486.<br clear="none">
</div>
<div><br clear="none">
</div>
<div>Ted</div>
</div>
<br clear="none">
<div>
<div
id="m_2522374105748133428yiv3165671766yqt07356">
<div dir="ltr">On Mon, Jun 30, 2025 at 8:41 AM
Steve Isenberg via LCTG <<a
rel="nofollow noopener noreferrer"
shape="rect"
href="mailto:lctg@lists.toku.us"
target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">lctg@lists.toku.us</a>>
wrote:<br clear="none">
</div>
<blockquote
style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="ltr">
<div
style="font-family:sans-serif;font-size:small;color:rgb(11,83,148)">Sad
news. He will be missed.</div>
<br clear="none">
<div>
<div dir="ltr">---------- Forwarded
message ---------<br clear="none">
From: <strong>Bea Kleppner</strong> <span><<a
rel="nofollow noopener noreferrer"
shape="rect"
href="mailto:bkleppner@gmail.com"
target="_blank"
moz-do-not-send="true"
class="moz-txt-link-freetext">bkleppner@gmail.com</a>></span><br
clear="none">
Date: Sun, Jun 29, 2025 at 11:42 PM<br
clear="none">
Subject: Dan Kleppner<br clear="none">
To: Steve Isenberg <<a
rel="nofollow noopener noreferrer"
shape="rect"
href="mailto:smisenberg@gmail.com"
target="_blank"
moz-do-not-send="true"
class="moz-txt-link-freetext">smisenberg@gmail.com</a>><br
clear="none">
</div>
<br clear="none">
<br clear="none">
<div>
<div dir="ltr"><br clear="none">
<span style="font-size:14.6667px">Dear
Steve,</span>
<div><span
style="font-size:14.6667px">I am
so sorry to write you the</span><br
clear="none"
style="font-size:14.6667px">
<span style="font-size:14.6667px">sad
news that my Dan unexpectedly
died at Stanford hospital in
California on June 16</span><br
clear="none"
style="font-size:14.6667px">
<span style="font-size:14.6667px">Dan
and I were in Palo Alto</span><br
clear="none"
style="font-size:14.6667px">
<span style="font-size:14.6667px">to
attend our grandson Darwin's
high school graduation. </span><br
clear="none"
style="font-size:14.6667px">
<br clear="none"
style="font-size:14.6667px">
<span style="font-size:14.6667px">On
Father's Day Dan enjoyed his
favorite meal in Sofie's pretty
garden.</span><br clear="none"
style="font-size:14.6667px">
<span style="font-size:14.6667px">His
last words were a toast to honor
Darwin and the young generation
who, he said, will be doing
exciting new things.</span><br
clear="none"
style="font-size:14.6667px">
<span style="font-size:14.6667px">Then
he collapsed. Despite CPR and
ambulance to hospital, he did
not regain consciousness.</span></div>
<div><span
style="font-size:14.6667px">A
link to his obituary in the
Washington Post is below. A </span><span
style="font-size:14.6667px">memorial
will </span><span
style="font-size:14.6667px">be
held probably at MiT. I will let
you know.</span></div>
<div><span
style="font-size:14.6667px">There
is solace in the long and happy
life we had together and with
his friends.He very much enjoyed
his associattion with the
Lexington computer and
technology group. </span><br
clear="none"
style="font-size:14.6667px">
<span style="font-size:14.6667px">He
enjoyed life and was optimistic
to the end.</span><br
clear="none"
style="font-size:14.6667px">
<br clear="none"
style="font-size:14.6667px">
<span style="font-size:14.6667px">Sadly,</span><br
clear="none"
style="font-size:14.6667px">
<span style="font-size:14.6667px">Beatrice
Kleppner</span></div>
<div><span
style="font-size:14.6667px;background-color:rgb(255,255,255)"><br
clear="none">
</span></div>
<div><span
style="font-size:14.6667px;background-color:rgb(255,255,255)"><br
clear="none"
id="m_2522374105748133428yiv3165671766m_1939816872368294636m_1172947083281014899lineBreakAtBeginningOfSignature">
</span>
<div dir="ltr">Sent from my iPhone</div>
<div dir="ltr"><br clear="none">
<blockquote type="cite"><br
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<span class="gmail_signature_prefix">-- </span><br>
<div dir="ltr" class="gmail_signature">
<div dir="ltr"><i><font color="#000000">Regards,</font></i>
<div><i style="background-color:rgb(255,255,255)"><font
color="#000000">Shireen Ahmed</font></i></div>
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